Absolute Zero

Absolute Zero MDCAT MCQs with answers

5 past paper MCQs on Absolute Zero, from the Gases unit of MDCAT Chemistry. The year each question appeared is shown where known; tap “Show answer” for the correct option and a short solution.

Read the notes first Practise the unit as a quiz

1.A graph between volume and temperature gives a straight line which cuts the temperature axis at: (MDCAT 2020)

  1. $273^\circ$C
  2. $-273^\circ$C
  3. $540^\circ$C
  4. $0^\circ$C
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Correct answer: (b) $-273^\circ$C

Extrapolated to zero volume the line meets the axis at absolute zero, $-273^\circ$C.

2.The starting point of the Kelvin scale is: (MDCAT 2020)

  1. 0 K
  2. 100 K
  3. $-210$ K
  4. $-273.15$ K
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Correct answer: (a) 0 K

The Kelvin scale begins at absolute zero, which is 0 K by definition.

3.Which of the following is true about pressure for an ideal gas at -273°C? (UHS MDCAT 2025)

  1. P=1atm
  2. P=2atm
  3. P=3atm
  4. P=0 atm
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Correct answer: (d) P=0 atm

At absolute zero the molecular motion stops, so the gas would exert no pressure at all.

4.Absolute zero temperature is equal to: (NUMS MDCAT 2025)

  1. 0°C
  2. -173°C
  3. -273°C
  4. -373°C
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Correct answer: (c) -273°C

Absolute zero is $-273.15^{\circ}\mathrm{C}$, the temperature at which molecular motion would cease.

5.The temperature at which volume of all the ideal gases becomes zero is: (PMC MDCAT 2022)

  1. 0 K
  2. 0˚C
  3. 0˚F
  4. 32˚F
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Correct answer: (a) 0 K

Extrapolating the volume line of any gas to zero brings it to absolute zero.

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