MDCAT 2018

MDCAT 2018 Past Paper with Answers (All Subjects)

159 MCQs from MDCAT 2018 in our bank, each with its correct answer and a solution. This is a recall-based collection gathered from students and past-paper books, not the complete official paper.

MDCAT 2018 by subject

Biology

1.In viruses, a combined structure formed by core (Nucleic Acid) and capsid is: (UHS MDCAT 2018)

  1. Nucleocapsid
  2. Prion
  3. Envelope
  4. Capsomeres
Show answer

Correct answer: (a) Nucleocapsid

The genome with its capsid together are the nucleocapsid.

2.Phages which show lysogenic cycle are known as: (UHS MDCAT 2018)

  1. Enveloped Phage
  2. Virulent Phage
  3. Temperate phages
  4. Bacteriophage
Show answer

Correct answer: (c) Temperate phages

A temperate phage integrates its genome and lies dormant instead of bursting the cell at once.

3.The enzymes required for the Kreb cycle are found in ________. (UHS MDCAT 2018)

  1. F1 particles
  2. Lysosomes
  3. Cytoplasm
  4. Matrix
Show answer

Correct answer: (d) Matrix

The Krebs cycle enzymes are dissolved in the mitochondrial matrix.

4.In aerobic respiration (UHS MDCAT 2018)

  1. Pyruvate is completely oxidized to form carbon dioxide and water
  2. Pyruvate is completely oxidized to form oxygen and water
  3. Pyruvate carboxylated to produce citrate
  4. Pyruvate is converted to ethanol and carbon dioxide
Show answer

Correct answer: (a) Pyruvate is completely oxidized to form carbon dioxide and water

With oxygen present the pyruvate is oxidized right through to carbon dioxide and water.

5.At the last step of Glycolysis, which of the following compound is formed: (UHS MDCAT 2018)

  1. Pyruvic acid/ Pyruvate
  2. Lactic acid
  3. Ethyl Alcohol
  4. Fructose Phosphate
Show answer

Correct answer: (a) Pyruvic acid/ Pyruvate

Glycolysis ends at pyruvate.

6.The enzymes required in Glycolysis are present in: (UHS MDCAT 2018)

  1. Golgi Apparatus
  2. Cell cytoplasm
  3. Inner Mitochondrial Membrane
  4. Matrix of Mitochondria
Show answer

Correct answer: (b) Cell cytoplasm

Glycolysis needs no organelle and goes on in the cytoplasm.

7.Glycosidic bond is formed by the: (UHS MDCAT 2018)

  1. Removal of Oxygen
  2. Addition of Oxygen
  3. Removal of water
  4. Addition of water
Show answer

Correct answer: (c) Removal of water

The glycosidic bond is made by condensation, with a molecule of water lost.

8.The number and sequence of amino acids along a polypeptide chain is called _______ structure of a protein. (UHS MDCAT 2018)

  1. Quaternary
  2. Tertiary
  3. Primary
  4. Secondary
Show answer

Correct answer: (c) Primary

The order of the amino acids is the primary structure.

9.Which of the following holds the alpha helix of protein in its place: (UHS MDCAT 2018)

  1. R group
  2. Disulfide bond
  3. Amino group
  4. Hydrogen bond
Show answer

Correct answer: (d) Hydrogen bond

Hydrogen bonds between the peptide groups hold the coil of the alpha helix.

10.Which of the following is Unsaturated “Fatty Acid”? (UHS MDCAT 2018)

  1. Stearic Acid
  2. Palmitic Acid
  3. Butyric Acid
  4. Oleic Acid
Show answer

Correct answer: (d) Oleic Acid

Oleic acid has a double bond in its chain; the other three are saturated.

11.Which lipid is hydrophilic and soluble? (UHS MDCAT 2018)

  1. Triglycerides
  2. Phospholipids
  3. Waxes
  4. Terpenoids
Show answer

Correct answer: (b) Phospholipids

A phospholipid has a charged phosphate head that dissolves in water and two tails that do not.

12.A complete turn of the double helix of DNA comprises of: (UHS MDCAT 2018)

  1. 34 nm
  2. 3.4 Angstrom
  3. 3.4 nm
  4. 34 micrometers
Show answer

Correct answer: (c) 3.4 nm

One complete turn of the helix is ten base pairs, that is $3.4\,\mathrm{nm}$.

13.Single ringed pyrimidines are: (UHS MDCAT 2018)

  1. Uracil, Cytosine and Thymine
  2. Cytosine, Guanine and Uracil
  3. Adenine and Guanine
  4. Cytosine, Adenine and Thymine
Show answer

Correct answer: (a) Uracil, Cytosine and Thymine

The pyrimidines are cytosine, thymine and uracil, each with a single ring.

14.The region of the chromosome or, more specifically, the length of the DNA molecule, which has a particular function is called _______. (UHS MDCAT 2018)

  1. Kinetochore
  2. Locus
  3. Allele
  4. Gene
Show answer

Correct answer: (d) Gene

A gene is the length of DNA that carries the information for one function.

15.The ability to distinguish between two separate points/objects is: (UHS MDCAT 2018)

  1. Magnification
  2. Fractionation
  3. Centrifugation
  4. Resolution
Show answer

Correct answer: (d) Resolution

Resolution is the power to show two close points as separate.

16.Rod-shaped bacteria are known as _______ (UHS MDCAT 2018)

  1. Spirilla
  2. Bacilli
  3. Spirochete
  4. Cocci
Show answer

Correct answer: (b) Bacilli

A rod shaped bacterium is a bacillus.

17.If lipopolysaccharides did not appear in the wall of bacteria on staining then it will be known as ________. (UHS MDCAT 2018)

  1. Gram negative
  2. Gram positive
  3. Capsule
  4. Both Gram positive & negative
Show answer

Correct answer: (b) Gram positive

Lipopolysaccharide belongs to the outer membrane of a gram negative wall.

18.The cisternae breaks up into vesicles form _______ , ______ of Golgi complex. (UHS MDCAT 2018)

  1. Convex, maturing face
  2. Concave, forming face
  3. Convex, forming face
  4. Concave, maturing face
Show answer

Correct answer: (d) Concave, maturing face

Vesicles bud from the concave maturing face; the convex face receives from the reticulum.

19.Site of protein synthesis in cells are: (UHS MDCAT 2018)

  1. Ribosomes
  2. Endoplasmic Reticulum
  3. Nucleolus
  4. Smooth Endoplasmic Reticulum
Show answer

Correct answer: (a) Ribosomes

Proteins are built on the ribosomes.

20.Tonoplast bounds which organelle: (UHS MDCAT 2018)

  1. Golgi complex
  2. Nucleus
  3. Endoplasmic Reticulum
  4. Vacuoles
Show answer

Correct answer: (d) Vacuoles

The membrane round a vacuole is the tonoplast.

21.These structures are involved in the breakdown of old organelles: (UHS MDCAT 2018)

  1. Leucoplasts
  2. Peroxisomes
  3. Glyoxysomes
  4. Lysosomes
Show answer

Correct answer: (d) Lysosomes

Lysosomes digest worn out organelles, which is autophagy.

22.In cross-section each Centriole consist of nine (each in triplets) of: (UHS MDCAT 2018)

  1. Microfilaments
  2. Microvilli
  3. Microtubules
  4. Intermediate filaments
Show answer

Correct answer: (c) Microtubules

A centriole is nine triplets of microtubules arranged in a cylinder.

23.Ribosomes are made up of _______ and _________. (UHS MDCAT 2018)

  1. Proteins and carbohydrates
  2. RNA and lipid
  3. RNA and proteins
  4. RNA and carbohydrates
Show answer

Correct answer: (c) RNA and proteins

A ribosome is ribosomal RNA together with protein.

24.Synthesis of microtubules increases in: (UHS MDCAT 2018)

  1. M phase
  2. S phase
  3. G1 phase
  4. G2 phase
Show answer

Correct answer: (d) G2 phase

The tubulin of the spindle is made in G2, after replication and before division.

25.They serve as a scaffold for formation of higher order chromatin structure: (UHS MDCAT 2018)

  1. Nucleosome
  2. Nucleus
  3. Chromosomes
  4. Histones
Show answer

Correct answer: (a) Nucleosome

The nucleosome, DNA wound on its histone octamer, is the first level of chromosome coiling.

26.Taste buds on the tongue are example of: (UHS MDCAT 2018)

  1. Pressure receptors
  2. Chemoreceptors
  3. Thermoreceptors
  4. Photoreceptors
Show answer

Correct answer: (b) Chemoreceptors

Taste buds respond to molecules dissolved in saliva, so they are chemoreceptors.

27.How many sodium ions are pumped out in response to two potassium ions transported into the membrane? (UHS MDCAT 2018)

  1. 2
  2. 3
  3. 4
  4. 1
Show answer

Correct answer: (b) 3

The pump drives three sodium ions out for every two potassium ions in.

28.When a nerve impulse jumps from one node of Ranvier to the next in a myelinated neuron, it’s called __________. (UHS MDCAT 2018)

  1. Synapses
  2. Saltatory conduction
  3. Resting potential
  4. Membrane potential
Show answer

Correct answer: (b) Saltatory conduction

The impulse jumps from node to node, which is saltatory conduction.

29.In the nervous system chemical messengers are called ______. (UHS MDCAT 2018)

  1. Neurotransmitters
  2. Hormones
  3. CHemoreceptors
  4. Enzymes
Show answer

Correct answer: (a) Neurotransmitters

The chemicals that cross a synapse are the neurotransmitters.

30.A non-protein part which is essential for proper functioning of enzyme is called: (UHS MDCAT 2018)

  1. Additional factor
  2. Cofactor
  3. Efficient co factor
  4. Extra factor
Show answer

Correct answer: (b) Cofactor

A non-protein part an enzyme needs is a cofactor.

31.The temperature that promotes the maximum activity of enzymes is referred to as ______. (UHS MDCAT 2018)

  1. Fixed temperature
  2. Optimum temperature
  3. Controlled temperature
  4. Active temperature
Show answer

Correct answer: (b) Optimum temperature

The temperature at which an enzyme is fastest is its optimum temperature.

32.If the molecule can bind to another site of the enzyme rather than the true active site, it is referred to as ______ (UHS MDCAT 2018)

  1. Competitive inhibitors
  2. Allosteric inhibition
  3. Noncompetitive inhibitors
  4. Irreversible inhibition
Show answer

Correct answer: (c) Noncompetitive inhibitors

A molecule binding away from the active site is a non-competitive inhibitor.

33.Divergent Evolution produces: (UHS MDCAT 2018)

  1. Vital Organs
  2. Homologous Organs
  3. Vestigial Organs
  4. Analogous Organs
Show answer

Correct answer: (b) Homologous Organs

Divergence from a common ancestor leaves organs of one plan put to different uses.

34.Organs specialized to perform different functions but structurally alike are: (UHS MDCAT 2018)

  1. Analogous organs
  2. Homologous organs
  3. Autologous organs
  4. Anuclogous organs
Show answer

Correct answer: (b) Homologous organs

Organs of the same plan put to different work are homologous.

35.Process ensuring the survival of species over long periods of time, even though individual members of the species die. (UHS MDCAT 2018)

  1. Reproduction
  2. Adaptability
  3. Mitosis
  4. Respiration
Show answer

Correct answer: (a) Reproduction

Reproduction is what carries the species on after its members die.

36.In human female, the egg is fertilized in: (UHS MDCAT 2018)

  1. Ovary
  2. Vagina
  3. Oviduct
  4. Uterus
Show answer

Correct answer: (c) Oviduct

Fertilization takes place in the upper third of the oviduct.

37.Which hormone is released in females in response to FSH from the pituitary gland? (UHS MDCAT 2018)

  1. Estrogen
  2. ADH
  3. Oxytocin
  4. Progesterone
Show answer

Correct answer: (a) Estrogen

FSH ripens the follicle, and the growing follicle secretes oestrogen.

38.Which of the following hormones acts on the uterus wall for thickening? (UHS MDCAT 2018)

  1. Progesterone
  2. Zona pellucida
  3. Follicle stimulating hormone
  4. Oxytocin
Show answer

Correct answer: (a) Progesterone

Progesterone from the corpus luteum thickens the endometrium and holds it ready.

39.Which hormone causes the contraction walls of the uterus during the process of birth? (UHS MDCAT 2018)

  1. FSH
  2. STH
  3. Oxytocin
  4. LTH
Show answer

Correct answer: (c) Oxytocin

Oxytocin drives the contractions of labour.

40.Scapula is a: (UHS MDCAT 2018)

  1. Tail bone
  2. Hip bone
  3. Skull bone
  4. Shoulder bone
Show answer

Correct answer: (d) Shoulder bone

The scapula is the shoulder blade.

41.Skull, vertebral column, ribs, and sternum forms: (UHS MDCAT 2018)

  1. Appendicular skeleton
  2. Hydrostatic skeleton
  3. Exoskeleton
  4. Axial skeleton
Show answer

Correct answer: (d) Axial skeleton

The skull, vertebral column, ribs and sternum make the axial skeleton.

42.Coccyx vertebrae are located in: (UHS MDCAT 2018)

  1. Cervical region
  2. Lumbar region
  3. Pelvic region
  4. Thoracic region
Show answer

Correct answer: (c) Pelvic region

The coccyx is the tail bone at the base of the vertebral column, in the pelvis.

43.Which combination is the example of ball and socket joints: (UHS MDCAT 2018)

  1. Hip and shoulder joints
  2. Hip and knee joints
  3. Shoulder and knee joints
  4. Hip and elbow joints
Show answer

Correct answer: (a) Hip and shoulder joints

The hip and the shoulder are both ball and socket joints.

44.When two or more alleles do not show complete dominance or both the alleles are expressing independently in heterozygotic condition. Such a condition is called: (UHS MDCAT 2018)

  1. Complete dominance
  2. Over dominance
  3. Codominance
  4. Incomplete dominance
Show answer

Correct answer: (c) Codominance

Codominant alleles are both expressed in the heterozygote.

45.Which one of the following is Multiple allelic characters? (UHS MDCAT 2018)

  1. Colour of flower in pea plant
  2. Blood group of the human being
  3. Shape of seed in pea plant
  4. Length of stem in pea plant
Show answer

Correct answer: (b) Blood group of the human being

The ABO system has three alleles, so it is an example of multiple alleles.

46.Chance of a cross over between two loci is directly proportional to their (UHS MDCAT 2018)

  1. Thickens
  2. Width
  3. Length
  4. Distance
Show answer

Correct answer: (d) Distance

The further apart two loci lie, the likelier a chiasma falls between them.

47.There are ______ number of linkage groups in humans. (UHS MDCAT 2018)

  1. 46
  2. 22
  3. 80
  4. 23
Show answer

Correct answer: (d) 23

A linkage group is one chromosome of a haploid set, and the human haploid number is 23.

48._________ is the exact position of a gene on the chromosome. (UHS MDCAT 2018)

  1. Trait
  2. Centromere
  3. Genotype
  4. Locus
Show answer

Correct answer: (d) Locus

The place a gene occupies on the chromosome is its locus.

49.Crossing over takes place during _____ of meiosis. (UHS MDCAT 2018)

  1. Prophase I
  2. Telophase I
  3. Metaphase I
  4. Anaphase I
Show answer

Correct answer: (a) Prophase I

Homologues pair and exchange segments at prophase I.

50.Which one of the following cells does not have nucleus: (UHS MDCAT 2018)

  1. Eosinophils
  2. Neutrophils
  3. Basophils
  4. Platelets
Show answer

Correct answer: (d) Platelets

Platelets are fragments of megakaryocytes and carry no nucleus.

51.The thickest chamber of the human heart is: (UHS MDCAT 2018)

  1. Left atrium
  2. Right atrium
  3. Right ventricle
  4. Left ventricle
Show answer

Correct answer: (d) Left ventricle

The left ventricle drives blood round the whole body, so its wall is the thickest.

52.Which statement is correct about atrial systole? (UHS MDCAT 2018)

  1. Atria relax and ventricles contract
  2. Atria contract and ventricle also contract
  3. Ventricles remain relaxed while atria contracts
  4. Atria and ventricles are relaxed
Show answer

Correct answer: (c) Ventricles remain relaxed while atria contracts

In atrial systole the atria contract while the ventricles are still relaxed and filling.

53.Which one of the following act as a PACEMAKER in heart: (UHS MDCAT 2018)

  1. Bundle of His
  2. Atrioventricular node
  3. Atrioventricular bundles of fibers
  4. Sinoatrial node
Show answer

Correct answer: (d) Sinoatrial node

The sinoatrial node sets the rhythm of the heart.

54.Cell-mediated immune response is given by: (UHS MDCAT 2018)

  1. T-lymphocytes
  2. B lymphocytes
  3. Neutrophils
  4. Macrophages
Show answer

Correct answer: (a) T-lymphocytes

Cell mediated immunity is carried by the T lymphocytes.

55.In immunoglobulins / antibodies, Two light chains and two heavy chains are linked to each other by: (UHS MDCAT 2018)

  1. Covalent bonds
  2. Hydrogen bonds
  3. Ionic bonds
  4. Disulphide bonds
Show answer

Correct answer: (d) Disulphide bonds

The four chains of an antibody are held together by disulphide bridges.

56.Antivenom given after a snake bite venom is an example of: (UHS MDCAT 2018)

  1. Natural passive immunity
  2. Artificial active immunity
  3. Natural active immunity
  4. Artificial passive immunity
Show answer

Correct answer: (d) Artificial passive immunity

Antibodies received ready made give passive immunity, and here they are given artificially.

57.Which of the following statements is correct about the respiratory pigments? (UHS MDCAT 2018)

  1. Myoglobin and Haemoglobin has higher affinity for nitrogen
  2. Cyanide and Haemoglobin has a low affinity for oxygen
  3. Myoglobin has more affinity for oxygen as compared to haemoglobin
  4. Albumin, Globulin and Globin proteins are present in respiratory pigments
Show answer

Correct answer: (c) Myoglobin has more affinity for oxygen as compared to haemoglobin

Myoglobin holds oxygen more tightly than haemoglobin, so it takes it up in the muscle.

58.During breathing air from Pharynx enters to: (UHS MDCAT 2018)

  1. Trachea
  2. Bronchioles
  3. Alveoli
  4. Bronchi
Show answer

Correct answer: (a) Trachea

Air passes from the pharynx through the larynx into the trachea.

59.The low levels of Surfactant produced by Alveolar epithelium causes: (UHS MDCAT 2018)

  1. Respiratory distress syndrome
  2. Emphysema
  3. Bronchitis
  4. Asthma
Show answer

Correct answer: (a) Respiratory distress syndrome

Without surfactant the alveoli collapse at each breath out, which is respiratory distress syndrome.

60.Gradual breakdown of the alveolar wall leads to which type of disease in a smoker? (UHS MDCAT 2018)

  1. Coronary heart disease
  2. Bronchitis
  3. Emphysema
  4. Asthma
Show answer

Correct answer: (c) Emphysema

Emphysema is the destruction of the alveolar walls, which cuts the surface for gas exchange.

61.The term “Loss of appetite” refers to disease: (UHS MDCAT 2018)

  1. Botulism
  2. Anorexia nervosa
  3. Obesity
  4. Bulemia nervosa
Show answer

Correct answer: (b) Anorexia nervosa

Anorexia nervosa is the refusal of food and the loss of appetite that goes with it.

62.The first part of the large intestine is: (UHS MDCAT 2018)

  1. Colon
  2. Appendix
  3. Caecum
  4. Rectum
Show answer

Correct answer: (c) Caecum

The caecum is the pouch at the beginning of the large intestine.

63.Number of salivary glands found in the human oral cavity. (UHS MDCAT 2018)

  1. 4
  2. 3
  3. 6
  4. 2
Show answer

Correct answer: (c) 6

There are three pairs of salivary glands, six in all.

64.Salivary Amylase begins to digest Starch to shorter polysaccharides and then to: (UHS MDCAT 2018)

  1. Glucose
  2. Maltose
  3. Sucrose
  4. Lactose
Show answer

Correct answer: (b) Maltose

Amylase breaks starch to dextrins and then to the disaccharide maltose.

65.The capillaries of glomerulus rejoin to form an _______. (UHS MDCAT 2018)

  1. Efferent arteriole
  2. Afferent arteriole
  3. Peritubular capillaries
  4. Collecting duct
Show answer

Correct answer: (a) Efferent arteriole

The glomerular capillaries gather again into the efferent arteriole, which is narrower than the afferent one.

66.When filtration is completed the waste products through distal tube of Nephrons empties to: (UHS MDCAT 2018)

  1. Efferent Arteriole
  2. Collecting Tubules
  3. Peritubular capillaries
  4. Proximal tubules
Show answer

Correct answer: (b) Collecting Tubules

The distal tubule empties into the collecting duct, which carries the urine down through the medulla.

67._________ hormone is released from the posterior lobe of the pituitary gland. (UHS MDCAT 2018)

  1. Adrenaline
  2. Thyroid stimulating hormone
  3. FSH
  4. Antidiuretic hormone
Show answer

Correct answer: (d) Antidiuretic hormone

The posterior pituitary releases antidiuretic hormone and oxytocin.

68.The hormone which controls the uptake of Sodium ions in kidney and its maintenance in blood plasma is: (UHS MDCAT 2018)

  1. Somatotrophic Hormone
  2. Aldosterone Hormone
  3. Gonadotrophic Hormone
  4. Thyroxine Hormone
Show answer

Correct answer: (b) Aldosterone Hormone

Aldosterone drives the sodium pumps of the distal tubule.

69.Keeping correct balance of ions and water in our body is called as: (UHS MDCAT 2018)

  1. Thermoregulation
  2. Osmoregulation
  3. Excretion
  4. Selective reabsorption
Show answer

Correct answer: (b) Osmoregulation

Keeping the water and solute balance right is osmoregulation.

70.Blood solute potential is controlled by the following hormone. (UHS MDCAT 2018)

  1. Estrogen
  2. Epinephrine
  3. Thyroxine
  4. Vasopressin
Show answer

Correct answer: (d) Vasopressin

Vasopressin, that is antidiuretic hormone, sets how much water the kidney returns to the blood.

71.Urea cycle is the detoxification of: (UHS MDCAT 2018)

  1. Creatinine
  2. Amino acids
  3. Carbon dioxide
  4. Ammonia
Show answer

Correct answer: (d) Ammonia

The liver turns the toxic ammonia of deamination into urea.

72.DNA made by joining pieces from two or more different sources: (UHS MDCAT 2018)

  1. Probes
  2. Restriction endonuclease
  3. Mutated DNA
  4. Recombinant DNA
Show answer

Correct answer: (d) Recombinant DNA

DNA carrying lengths from two organisms is recombinant DNA.

73.Deficiency of enzyme ______ causes combined immunodeficiency syndrome. (UHS MDCAT 2018)

  1. Adenosine transcriptase
  2. Adenosine transaminase
  3. Adenosine polymerase
  4. Adenosine deaminase
Show answer

Correct answer: (d) Adenosine deaminase

Adenosine deaminase deficiency is the commonest cause of severe combined immunodeficiency.

74.Chemical nature of primers used in the PCR process is _______. (UHS MDCAT 2018)

  1. RNA
  2. Protein
  3. Carbohydrate
  4. DNA
Show answer

Correct answer: (d) DNA

A primer is a short single strand of DNA that the polymerase can extend.

75.By PCR we mean: (UHS MDCAT 2018)

  1. Polymerase chronic reaction
  2. Polymerase chain reaction
  3. Polymerase copy reaction
  4. Polymerase cross reaction
Show answer

Correct answer: (b) Polymerase chain reaction

PCR stands for polymerase chain reaction.

76.Enzyme used by the Bacteria to cut the DNA of the invading Virus for its protection is: (UHS MDCAT 2018)

  1. Restriction Exonuclease
  2. Restriction Ligase
  3. Restriction Endonuclease
  4. DNA polymerase
Show answer

Correct answer: (c) Restriction Endonuclease

A restriction endonuclease cuts the DNA at a specific sequence within the molecule.

Chemistry

77.The formula which shows the simplest whole number ratio for the atoms of different elements in a compound is: (UHS MDCAT 2018)

  1. Ionic formula
  2. Structural formula
  3. Empirical formula
  4. Molecular formula
Show answer

Correct answer: (c) Empirical formula

The simplest whole number ratio of the atoms is the empirical formula.

78.While finding the relative atomic mass, which of the following standard is used to compare the atomic mass of chlorine (35.5 amu) (UHS MDCAT 2018)

  1. Carbon – 13
  2. Neon – 20
  3. Carbon – 12
  4. Nucleon number
Show answer

Correct answer: (c) Carbon – 12

Atomic masses are referred to carbon-12, taken as exactly twelve units.

79.3.0 mole of Calcium will contain _____ g of Calcium. (UHS MDCAT 2018)

  1. 105 g
  2. 120 g
  3. 80 g
  4. 100 g
Show answer

Correct answer: (b) 120 g

$3.0\times40$ is $120\,\mathrm{g}$.

80.Which is the correct electronic configuration of Chromium (24Cr)? (UHS MDCAT 2018)

  1. 1s2, 2s2, 3s2, 2p6, 3p6, 4s2, 3d6
  2. 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d4
  3. 1s1, 2s2, 2p6, 3s2, 3p6, 3d6
  4. 1s2, 2s2, 2p6, 3s2, 3p6, 4s1, 3d5
Show answer

Correct answer: (d) 1s2, 2s2, 2p6, 3s2, 3p6, 4s1, 3d5

A half filled d subshell is stable, so chromium is $[\mathrm{Ar}]4s^1 3d^5$.

81.Gas is enclosed in a container of 20 cm3 with the moving piston. According to kinetic theory of gases, what will be the effect on freely moving molecules of the gas if temperature is increased from 20 C to 100 C? (UHS MDCAT 2018)

  1. Pressure will become one half
  2. Volume will be increased
  3. Temperature has no effect on freely moving molecules
  4. Colliding capability of molecule will become lower
Show answer

Correct answer: (b) Volume will be increased

The molecules move faster and strike the piston harder, so at constant pressure the gas expands.

82.Liquid in the container has a temperature 70°C. What will be the temperature on the Kelvin scale? (UHS MDCAT 2018)

  1. 350 K
  2. 343 K
  3. 300 K
  4. 283 K
Show answer

Correct answer: (b) 343 K

$70+273$ is $343\,\mathrm{K}$.

83.Which of the following is the correct equation to calculate relative molecular mass of a gas. (UHS MDCAT 2018)

  1. M = mPR / VT
  2. M = PV / mRT
  3. M = mPRT / V
  4. M = mRT / PV
Show answer

Correct answer: (d) M = mRT / PV

From $PV=(m/M)RT$ it follows that $M=mRT/PV$.

84.The product of the concentrations of each ion in a saturated solution of a sparingly soluble salt at 298 K, raised to the power of their relative concentrations is: (UHS MDCAT 2018)

  1. Ksp
  2. Ka
  3. Kw
  4. Kb
Show answer

Correct answer: (a) Ksp

That product is the solubility product, $K_{sp}$.

85.According to Lowry – Bronsted Acid & Base Concept, H2O is: (UHS MDCAT 2018)

  1. An acid
  2. A base
  3. An amphoteric species
  4. A salt
Show answer

Correct answer: (c) An amphoteric species

Water can give a proton or take one, so it is amphoteric.

86.The catalyst used for the manufacture of H2SO4by contact process is: (UHS MDCAT 2018)

  1. SO3
  2. V2O5
  3. Fe2O3
  4. Pt/Pd
Show answer

Correct answer: (b) V2O5

Vanadium(V) oxide catalyses the oxidation of sulphur dioxide in the contact process.

87.Role of a catalyst in a chemical reaction is to: (UHS MDCAT 2018)

  1. Decreases yield of a reaction
  2. Decreases rate of a reaction
  3. Increase yield of product
  4. Increase rate of a reaction
Show answer

Correct answer: (d) Increase rate of a reaction

A catalyst offers a path of lower activation energy; it does not change the yield.

88.If concentration time graph of a reactant indicates a constant half life, then the order reaction with respect to that reactant is: (UHS MDCAT 2018)

  1. Zero order
  2. Half order
  3. Second order
  4. First order
Show answer

Correct answer: (d) First order

Only for a first order reaction is the half life independent of the concentration.

89.Reaction of water with quicklime results in the rise in the temperature of the system. Using the concept of an energy change, indicates the nature of the reaction? (UHS MDCAT 2018)

  1. Endothermic Reaction
  2. Non-Spontaneous Reaction
  3. Third Order Reaction
  4. Exothermic Reaction
Show answer

Correct answer: (d) Exothermic Reaction

Heat is given out, so the reaction is exothermic.

90.Which one of the following enthalpy changes is always exothermic? (UHS MDCAT 2018)

  1. Enthalpy of combustion
  2. Enthalpy of formation
  3. Enthalpy of atomization
  4. Enthalpy of solution
Show answer

Correct answer: (a) Enthalpy of combustion

Burning always gives out heat.

91.The standard electrode potential of hydrogen is arbitrarily taken at 298 K is ________ (UHS MDCAT 2018)

  1. 0.00 volt
  2. 0.10 volt
  3. 10.0 volt
  4. 1.00 volt
Show answer

Correct answer: (a) 0.00 volt

The standard hydrogen electrode is taken as zero.

92.The potential difference of an electrochemical cell is measured by: (UHS MDCAT 2018)

  1. Ammeter
  2. Voltmeter
  3. Galvanometer
  4. Calorimeter
Show answer

Correct answer: (b) Voltmeter

A high resistance voltmeter reads the emf without drawing appreciable current.

93.Which of the following molecules has the largest number of shared pairs of electrons? (UHS MDCAT 2018)

  1. C2H4
  2. N2
  3. CO2
  4. NH3
Show answer

Correct answer: (a) C2H4

Ethene has four carbon hydrogen bonds and a double bond between the carbons, six shared pairs in all.

94.Which option shows all the molecules with bond angle 109.5 degrees. (UHS MDCAT 2018)

  1. CH4, NH4+ , PH3
  2. SiCl4, H2O , BeCl2
  3. SiCl4, NH4+ , CH4
  4. CH4, CCl4, NH3
Show answer

Correct answer: (c) SiCl4, NH4+ , CH4

All three have four bond pairs and no lone pair, so all are regular tetrahedra.

95.Electron affinity of the atom is the energy released when: (UHS MDCAT 2018)

  1. Covalent bond of molecule is broken
  2. Electron is added to gaseous atom
  3. Electron is removed from gaseous atom
  4. Covalent bond is formed between the atoms
Show answer

Correct answer: (b) Electron is added to gaseous atom

Electron affinity is the energy given out when an electron is added to a gaseous atom.

96.In Period 2 and Period 3 maximum melting point shown by elements: (UHS MDCAT 2018)

  1. Nitrogen and Phosphorus
  2. Neon and Argon
  3. Lithium and Sodium
  4. Carbon and Silicon
Show answer

Correct answer: (d) Carbon and Silicon

Carbon and silicon are covalent networks bonded right through, so they melt highest in their periods.

97.Halogens are being used as fire extinguishers, mild antiseptic CFCs and many other organic chemicals, Which of the following halogen is used to kill the bacteria in drinking water. (UHS MDCAT 2018)

  1. Bromine
  2. Fluorine
  3. Chlorine
  4. Iodine
Show answer

Correct answer: (c) Chlorine

Chlorine is used to disinfect drinking water.

98.Down the group acid-base behaviour of metallic oxides of group 2 elements changes to: (UHS MDCAT 2018)

  1. More basic
  2. No change
  3. Less basic
  4. More acidic
Show answer

Correct answer: (a) More basic

The oxides grow more basic down the group as the metals grow more electropositive.

99.The shape of [Co(NH3)6]3+ complex is: (UHS MDCAT 2018)

  1. Linear
  2. Square planar
  3. Tetrahedral
  4. Octahedral
Show answer

Correct answer: (d) Octahedral

Six ligands round a central ion take the corners of an octahedron.

100.Ligands having two lone pair of electrons for donation to the central transition metal ion are known as: (UHS MDCAT 2018)

  1. Polydentate ligands
  2. Monodentate ligand
  3. Bidentate ligands
  4. Hexadentate ligands
Show answer

Correct answer: (c) Bidentate ligands

A ligand with two donor atoms is bidentate.

101.Butane molecules can have a maximum number of isomers. (UHS MDCAT 2018)

  1. 5
  2. 3
  3. 4
  4. 2
Show answer

Correct answer: (d) 2

Butane and 2-methylpropane are the only two.

102.The species which are produced by heterolytic bond breaking and can act as electron pair donors are known as: (UHS MDCAT 2018)

  1. Nucleophiles
  2. Cations
  3. Free radicals
  4. Anions
Show answer

Correct answer: (a) Nucleophiles

A species with a lone pair to give is a nucleophile.

103.Reaction mechanism of alkanes with halogens is known as; (UHS MDCAT 2018)

  1. Propagation
  2. Free radical substitution
  3. Addition
  4. Elimination
Show answer

Correct answer: (b) Free radical substitution

Halogenation of an alkane goes by free radicals, and a hydrogen is substituted.

104.Bromination of alkene is shown in the following reaction. This reaction is used for: (UHS MDCAT 2018)

  1. Detection of ketones
  2. Detection of double bond
  3. Identification of Primary and Secondary alcohols
  4. Detection of Aldehydes
Show answer

Correct answer: (b) Detection of double bond

Bromine water is decolourized by an alkene, which is the test for a double bond.

105.Which of the following acts as an electrophile in the electrophilic substitution of benzene with bromine? (UHS MDCAT 2018)

  1. Br+
  2. FeCl4+
  3. Fe2+
  4. Fe3+
Show answer

Correct answer: (a) Br+

The catalyst polarizes the bromine molecule into $\mathrm{Br^+}$, which attacks the ring.

106.Halothane is a halo derivative of: (UHS MDCAT 2018)

  1. Methane
  2. Ethane
  3. Methanol
  4. Ethanol
Show answer

Correct answer: (b) Ethane

Halothane is 2-bromo-2-chloro-1,1,1-trifluoroethane.

107.Which of the following acts as a nucleophile in the reaction of alkyl halide with alcoholic / aqueous ammonia? (UHS MDCAT 2018)

  1. H+
  2. NH3
  3. NO2+
  4. Br-
Show answer

Correct answer: (b) NH3

The lone pair of the nitrogen of ammonia attacks the carbon and displaces the halide.

108.Which compound is obtained by the elimination of bromopropane? (UHS MDCAT 2018)

  1. Propene
  2. Ether
  3. Aldehyde
  4. Ester
Show answer

Correct answer: (a) Propene

Losing hydrogen bromide from bromopropane leaves propene.

109.Why is it necessary to distill aldehyde formed from oxidation of primary alcohol through acidified potassium dichromate (VI) solution or acidified sodium dichromate (VI) solution? (UHS MDCAT 2018)

  1. Aldehyde formed may be oxidized further to carboxylic acid concerned
  2. Aldehyde formed is unstable and decompose back to original precursor i.e. primary alcohol
  3. Aldehyde may be oxidised further to a ketone
  4. Aldehyde formed may react with primary alcohol, the original reactant.
Show answer

Correct answer: (a) Aldehyde formed may be oxidized further to carboxylic acid concerned

The aldehyde boils below the alcohol, so distilling it off as it forms keeps it from being oxidized further.

110.Select one which is alcohol. (UHS MDCAT 2018)

  1. CH3- CH2- Br
  2. CH3- O – CH3
  3. CH3COOH
  4. CH3- CH2- OH
Show answer

Correct answer: (d) CH3- CH2- OH

Ethanol carries the hydroxyl group on a saturated carbon, so it is an alcohol.

111.Alcohol in which carbon atom bonded to OH group is further attached with three alkyl group is: (UHS MDCAT 2018)

  1. Tertiary alcohol
  2. Primary alcohol
  3. Aromatic alcohol
  4. Secondary alcohol
Show answer

Correct answer: (a) Tertiary alcohol

A carbinol carbon carrying three alkyl groups makes a tertiary alcohol.

112.Which one of the following compounds is known as tertiary alcohol? (UHS MDCAT 2018)

  1. 1 – Propanol
  2. 2- methyl – 2- propanol
  3. 2- methyl – 1- propanol
  4. 2 – propanol
Show answer

Correct answer: (b) 2- methyl – 2- propanol

2-methylpropan-2-ol carries three methyl groups on the carbinol carbon.

113.Which of the following compounds is solid at room temperature? (UHS MDCAT 2018)

  1. Ethanol
  2. Butane
  3. Methanol
  4. Phenol
Show answer

Correct answer: (d) Phenol

Phenol melts at about $41^{\circ}\mathrm{C}$, so it is a solid at room temperature.

114.Which one of the following reagents is used to distinguish between aldehydes and ketones? (UHS MDCAT 2018)

  1. Alkaline Iodine
  2. Tollen’s Reagent
  3. Bromine
  4. 2, 4 DNPH
Show answer

Correct answer: (b) Tollen’s Reagent

Tollens’ reagent leaves a silver mirror with an aldehyde and nothing with a ketone.

115.Which compound will be produced by the oxidation of ethanal by acidified K2Cr2O7 ? (UHS MDCAT 2018)

  1. Ethene
  2. Ethanol
  3. Ethanoic acid
  4. Ethanone
Show answer

Correct answer: (c) Ethanoic acid

Acidified dichromate oxidizes the aldehyde on to the acid.

116.Which mechanism of reactions is shown by carbonyl compounds? (UHS MDCAT 2018)

  1. Electrophilic addition
  2. Electrophilic substitution
  3. Free radical substitution
  4. Nucleophilic addition
Show answer

Correct answer: (d) Nucleophilic addition

The carbonyl carbon is electron poor, so a nucleophile adds to it.

117.The dilute solution of ______ is called vinegar. (UHS MDCAT 2018)

  1. Formic acid
  2. Oxalic acid
  3. Benzoic acid
  4. Acetic acid
Show answer

Correct answer: (d) Acetic acid

Vinegar is dilute acetic, that is ethanoic, acid.

118.Which one will act as a strong acid? (UHS MDCAT 2018)

  1. Chloroethanoic acid
  2. Ethanoic acid
  3. Trichloroethanoic acid
  4. Dichloroethanoic acid
Show answer

Correct answer: (c) Trichloroethanoic acid

Three chlorine atoms pull hardest on the carboxyl group, so that acid is the strongest.

119.Which product is formed by the reaction of carboxylic acid with alcohol? (UHS MDCAT 2018)

  1. Alkane
  2. Ether
  3. Aldehyde
  4. Ester
Show answer

Correct answer: (d) Ester

An acid and an alcohol give an ester and water.

120.Which one of the following compounds act as a catalyst when alcohols react with carboxylic acids. (UHS MDCAT 2018)

  1. Pt
  2. Conc. HNO3
  3. Ni
  4. Conc. H2SO4
Show answer

Correct answer: (d) Conc. H2SO4

Concentrated sulphuric acid catalyses the esterification and takes up the water.

121.Amino acids react with each other such that -COOH group of one amino acid reacts with the -NH2 group of another amino acid to give a condensed structure as shown below: (UHS MDCAT 2018)

  1. Ester linkage
  2. Peptide linkage
  3. Carbide linkage
  4. Azide linkage
Show answer

Correct answer: (b) Peptide linkage

The link between two amino acids is the peptide bond.

122.The stability in the following structure is due to the: (UHS MDCAT 2018)

  1. Weak van der Waal’s forces
  2. Disulfide bridges
  3. Presence of unpaired electron in the structure
  4. Hydrogen bonding between NH group of one peptide and CO group of another peptide
Show answer

Correct answer: (d) Hydrogen bonding between NH group of one peptide and CO group of another peptide

The helix is held by hydrogen bonds between the NH of one peptide group and the CO of another.

123.Which one of the following is the structure of Teflon? (UHS MDCAT 2018)

  1. (-CF2-CF2-)n
  2. (-CF2-CCl2-)n
  3. (-CH2-CH2-)n
  4. (-CF2-CH2-)n
Show answer

Correct answer: (a) (-CF2-CF2-)n

Teflon is poly(tetrafluoroethene).

124.Nylon-6,6 is also called: (UHS MDCAT 2018)

  1. Poly styrene
  2. Polyester
  3. Polyamide
  4. Polyvinyl alcohol
Show answer

Correct answer: (c) Polyamide

Nylon-6,6 is a polyamide, made from a diamine and a diacid.

125.Which is the structure of polyvinyl chloride (polychloroethane)? (UHS MDCAT 2018)

  1. -[CCl2-CCl2]-
  2. -[HCCl-CH-Cl]-
  3. [H2C=CH-Cl]
  4. -[H2C-CH-Cl]-
Show answer

Correct answer: (d) -[H2C-CH-Cl]-

Poly(vinyl chloride) is a chain of $\mathrm{-CH_2-CHCl-}$ units.

Physics

126.If slope of velocity time graph is not constant at different points then body is moving with: (UHS MDCAT 2018)

  1. Uniform velocity
  2. changing acceleration
  3. Average acceleration
  4. Constant acceleration
Show answer

Correct answer: (b) changing acceleration

A changing slope means the acceleration is not constant.

127.A stone of mass 2.0 kg is dropped from a rest position 5.0 m above the ground. What is its velocity at a height of 3.0 m above the ground? (UHS MDCAT 2018)

  1. 12.5 m/s
  2. 6.3m/s
  3. 9.3 m/s
  4. 16.0 m/s
Show answer

Correct answer: (b) 6.3m/s

It has fallen $2\,\mathrm{m}$, so $v=\sqrt{2\times9.8\times2}$, about $6.3\,\mathrm{m\,s^{-1}}$.

128.A cyclist is travelling at 15 ms-1, she applies brakes so that she doesn’t collide with the wall in front of her at a distance of 18 m. Calculate the magnitude of deceleration. (UHS MDCAT 2018)

  1. 6.3 ms-1
  2. 5.3 ms-1
  3. 13 ms-1
  4. 12.5 ms-1
Show answer

Correct answer: (a) 6.3 ms-1

$v^2=2as$ gives $225=36a$, so the deceleration is about $6.3\,\mathrm{m\,s^{-2}}$.

129.Newton first law of motion is also known as: (UHS MDCAT 2018)

  1. Law of inertia
  2. Law of electromagnetism
  3. Law of universal gravity
  4. Law of conservation of momentum
Show answer

Correct answer: (a) Law of inertia

The first law says a body keeps its state unless a force acts, which is the law of inertia.

130.Energy consumed by 60 watt bulb in 2 minutes is equal to: (UHS MDCAT 2018)

  1. 7.2 kilo joules
  2. 720 joules
  3. 120 joules
  4. 72000 joules
Show answer

Correct answer: (a) 7.2 kilo joules

$60\times120$ is $7200\,\mathrm{J}$, that is $7.2\,\mathrm{kJ}$.

131.The rate at which work is being done is called: (UHS MDCAT 2018)

  1. Power
  2. Energy
  3. Density
  4. Force
Show answer

Correct answer: (a) Power

The rate of doing work is power.

132.A wheel starts rotating from result with angular acceleration of 2 rads-2 till its angular speed becomes 6 rad/s. The angular displacement of the wheel will be equal to: (UHS MDCAT 2018)

  1. 4 rad
  2. 9 rad
  3. 12 rad
  4. 7 rad
Show answer

Correct answer: (b) 9 rad

$\omega^2=2\alpha\theta$ gives $36=4\theta$, so $\theta$ is $9\,\mathrm{rad}$.

133.Which of the following gives the relationship between linear velocity and angular velocity? (UHS MDCAT 2018)

  1. v = rω
  2. v = rθ
  3. v=sω
  4. v=sθ
Show answer

Correct answer: (a) v = rω

The linear velocity is the radius times the angular velocity.

134.If the time period of the oscillation is 20 micro-sec, then what will be the frequency of that oscillating body? (UHS MDCAT 2018)

  1. 5000 Hz
  2. 50000 Hz
  3. 20000 Hz
  4. 1000 Hz
Show answer

Correct answer: (b) 50000 Hz

$f=1/T=1/(20\times10^{-6})$, that is $5\times10^4\,\mathrm{Hz}$.

135.A shock wave is produced due to an earthquake which makes the buildings move in the direction of the shock wave. Which progressive wave would this be? (UHS MDCAT 2018)

  1. Longitudinal wave
  2. Transverse wave
  3. Material wave
  4. Particle wave
Show answer

Correct answer: (a) Longitudinal wave

The ground moves along the direction the wave travels, so the wave is longitudinal.

136.In SHM the kinetic energy of the body is maximum when: (UHS MDCAT 2018)

  1. The body is at mean position
  2. The body is at extreme position from the mean
  3. The body is exactly half way down between mean and extreme position
  4. The body is somewhere between mean and extreme position
Show answer

Correct answer: (a) The body is at mean position

The speed is greatest as the body passes the mean position.

137.When the frequency of the applied force becomes equal to one of natural frequencies of body then the body oscillates with maximum displacement this phenomenon is called: (UHS MDCAT 2018)

  1. Heating
  2. Resonance
  3. Reverbnation
  4. Damping
Show answer

Correct answer: (b) Resonance

Driving a body at its own natural frequency is resonance.

138.Find the mean translational kinetic energy of ideal hydrogen gas at 17 degree Celcius. (UHS MDCAT 2018)

  1. 6.21 x 10-21J
  2. 5 x 10-21J
  3. 6.21 x 10-12J
  4. 6 x 10-21J
Show answer

Correct answer: (d) 6 x 10-21J

$\tfrac32kT=1.5\times1.38\times10^{-23}\times290$, about $6\times10^{-21}\,\mathrm{J}$.

139.If Cv= 5/2 R , Cpwill be: (UHS MDCAT 2018)

  1. 2 / 5 R
  2. 2 / 7 R
  3. 5 / 2 R
  4. 7 / 2 R
Show answer

Correct answer: (d) 7 / 2 R

$C_p=C_v+R=\tfrac52R+R$, that is $\tfrac72R$.

140.If one mole of an ideal gas is heated at constant pressure, then the first law of thermodynamics can be written as: (UHS MDCAT 2018)

  1. CpΔT = CvΔT + PΔV
  2. CvΔT = CpΔT + PΔV
  3. CpΔT = CvΔT + VΔP
  4. ΔCpT = ΔCvT + PΔV
Show answer

Correct answer: (a) CpΔT = CvΔT + PΔV

The heat put in at constant pressure raises the internal energy and does the work $P\Delta V$.

141.Force experienced per unit positive test charge at a point in an electric field is the definition of: (UHS MDCAT 2018)

  1. Electric potential energy
  2. Electric field strength
  3. Electric potential
  4. Electric field
Show answer

Correct answer: (b) Electric field strength

Force per unit positive test charge is the electric field strength.

142.Electric potential due to 2uC charge at distance of one meter is equal to: (UHS MDCAT 2018)

  1. 18 x 104volt
  2. 1.8 x 106volt
  3. 1.8 x 109volt
  4. 1.8 x 104volt
Show answer

Correct answer: (d) 1.8 x 104volt

$V=kq/r=9\times10^9\times2\times10^{-6}/1$, that is $1.8\times10^4\,\mathrm{V}$.

143.Kirchhoff’s first law is manifestation of: (UHS MDCAT 2018)

  1. Law of conservation of momentum
  2. Law of conservation mass
  3. Law of conservation of energy
  4. Law of conservation of charge
Show answer

Correct answer: (d) Law of conservation of charge

What flows into a junction must flow out, which is the conservation of charge.

144.When a potential difference is applied across the ends of a uniform wire of length l and radius r, a current I flows in the wire. If same potential difference is applied to the ends of another wire of the same material but of length 2l and radius 2r, the current in the wire is: (UHS MDCAT 2018)

  1. I/4
  2. 2I
  3. I
  4. I/2
Show answer

Correct answer: (b) 2I

Twice the length doubles the resistance and twice the radius quarters it, so $R$ halves and the current doubles.

145.Two long, parallel conductors which are free to move are arranged 1.0 cm apart. A steady current of 20 A flows in each of the conductors in the same direction. The conductors: (UHS MDCAT 2018)

  1. Remains stationary
  2. Move towards each other
  3. Move away from each other
  4. Move at right angles to each other
Show answer

Correct answer: (b) Move towards each other

Parallel currents in the same direction attract one another.

146.A neutron having mass equal to a proton (mp = 1.6 x 10-27 kg) is moving in a magnetic field of intensity 1.20 x 10-3 T with a speed of 2.0 x 107 ms-1 . What is the maximum force experienced by the neutron? (UHS MDCAT 2018)

  1. 3.84 x 10-15N
  2. 0
  3. 3.84 x 10-12N
  4. 38.4 x 10-15N
Show answer

Correct answer: (b) 0

A neutron carries no charge, so the magnetic field exerts no force on it.

147.E/m of an electron is given by the relationship. (UHS MDCAT 2018)

  1. e/m2(VB2r2)
  2. e/m=(V/Br)2
  3. e/m=V.r/B
  4. e/m=V/Br
Show answer

Correct answer: (d) e/m=V/Br

With the electric and magnetic forces balanced, $v=E/B$ and $e/m$ works out as $V/Br$.

148.A metal rod of length 10.0 cm is moving at a speed of 0.5 ms-1 in a direction perpendicular to a 0.20 T magnetic field. Find the emf produced in the rod. (UHS MDCAT 2018)

  1. 2.0 x 10-3V
  2. 0.50 x 10-2V
  3. 1.0 x 10-2V
  4. 1.0 x 10-3V
Show answer

Correct answer: (c) 1.0 x 10-2V

$\varepsilon=BLv=0.20\times0.10\times0.5$, that is $1.0\times10^{-2}\,\mathrm{V}$.

149.Lenz’s law in electromagnetic induction is the direct consequence of the principle of conservation of: (UHS MDCAT 2018)

  1. Energy
  2. Charge
  3. Momentum
  4. Mass
Show answer

Correct answer: (a) Energy

If the induced current helped the change, energy would be made from nothing.

150.In a practical transformer mutual induction between primary and secondary coils takes place. In such transformer what can be deduced about the power. (UHS MDCAT 2018)

  1. Power output = Power input
  2. Power output > Power input
  3. Power output ≥ Power input
  4. Power output < Power input
Show answer

Correct answer: (d) Power output < Power input

Some power is always lost as heat in the windings and the core, so the output falls short of the input.

151.What is the instantaneous power dissipated through a resistor of resistance 10 ohm if it is connected to an AC source of frequency 15 Hz at 1/180 sec if peak value is 20 V? (UHS MDCAT 2018)

  1. 10 W
  2. 100 W
  3. 40 W
  4. Cannot be determined
Show answer

Correct answer: (a) 10 W

At $t=1/180\,\mathrm{s}$ the phase is $30^{\circ}$, so $v=10\,\mathrm{V}$ and $P=v^2/R$ is $10\,\mathrm{W}$.

152.In case of half wave rectification the resistance of diode during negative half of A.C is: (UHS MDCAT 2018)

  1. Very high
  2. Very low
  3. A few ohms
  4. Negative
Show answer

Correct answer: (a) Very high

On the reverse half cycle the diode is reverse biased, so its resistance is enormous.

153.A 5 watt LED bulb converts 80% of the power into light photons wavelength 660 nm. What is the number of photons emitted from the bulb in one second. (UHS MDCAT 2018)

  1. 5.8 x 1034
  2. 7.5 x 1018
  3. 6.6 x 107
  4. 1.3 x 1019
Show answer

Correct answer: (d) 1.3 x 1019

$4\,\mathrm{W}$ of light with photons of $hc/\lambda=3.0\times10^{-19}\,\mathrm{J}$ gives about $1.3\times10^{19}$ photons a second.

154.Light photons, each of energy 3.5 x 10-19J falls on the cathode of a photocell. The current through the cell is reduced to zero by taking the cathode to a potential +0.25 V relative to anode. The work function of the cathode is: (UHS MDCAT 2018)

  1. 3.35 x 10-19J
  2. 3.5 x 10-19J
  3. 3.25 x 10-19J
  4. 3.1 x 10-19J
Show answer

Correct answer: (d) 3.1 x 10-19J

$W=hf-eV_s=3.5\times10^{-19}-1.6\times10^{-19}\times0.25$, that is $3.1\times10^{-19}\,\mathrm{J}$.

155.The de Broglie wavelength of an electron travelling with a speed of 1.0 x 107m/s is equal to, (h=6.6 x 10-34 Js and me= 9.1 x 10-31 kg) (UHS MDCAT 2018)

  1. 7.3 x 1011m
  2. 7.3 x 108m
  3. 7.3 x 10-11m
  4. 7.3 x 10-13m
Show answer

Correct answer: (c) 7.3 x 10-11m

$\lambda=h/mv=6.6\times10^{-34}/(9.1\times10^{-31}\times10^{7})$, about $7.3\times10^{-11}\,\mathrm{m}$.

156.What is the name of the energy which is released when an atom is formed from its constituent particles? (UHS MDCAT 2018)

  1. Atomic Energy
  2. Radioactive Energy
  3. Nuclear Energy
  4. Binding Energy
Show answer

Correct answer: (d) Binding Energy

The energy released when the nucleons come together is the binding energy.

157.Calculate the activity (decaying atom per unit time) of radioactive strontium – 90 having 6.7 x 1021 atoms at t = 0. Decay constant of strontium – 90 is 8.3 x 10-10 s-1 (UHS MDCAT 2018)

  1. 8.01 x 1010Bq
  2. 5.6 x 1011s-1
  3. 5.6 x 1012Bq
  4. 12 x 1011Bq
Show answer

Correct answer: (c) 5.6 x 1012Bq

$A=\lambda N=8.3\times10^{-10}\times6.7\times10^{21}$, about $5.6\times10^{12}\,\mathrm{Bq}$.

158.Calculate the half life of Bismuth-214 which has a decay constant of 4.3 x 10-4 s-1: (UHS MDCAT 2018)

  1. 2.9 x 10-3s
  2. 1.6 x 10^3 s
  3. 3.9 x 103s
  4. 2.9 x 103s
Show answer

Correct answer: (b) 1.6 x 10^3 s

$t_{1/2}=0.693/\lambda=0.693/4.3\times10^{-4}$, about $1.6\times10^3\,\mathrm{s}$.

English

159.In the following question, four alternative sentences are given. Choose the CORRECT one. (UHS MDCAT 2018)

  1. China is now the fashion around the world.
  2. China is now the fusion around the world.
  3. China is not the function around the world
  4. China is now fissure around the world.
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Correct answer: (a) China is now the fashion around the world.

Fashion is the word that fits: China is now what everyone follows.

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