Skip to content
Independent guidance for Pakistan's healthcare students
Student forum · Coming soonAggregate calculator
Medical AdmissionPAKISTAN
Practice MDCAT

LEARN AT YOUR OWN PACE

MDCAT Question Bank

Think through each question, then reveal the answer and explanation.

Take a practice test →

Use the MDCAT Question Bank to study by subject and try each question yourself.
Click Show Answer to check the correct choice, then take a practice test when you’re ready.

1009 available questions

Chemistry · Question 761

The number of atoms present in one molecule is called its:

  1. Basicity
  2. Atomicity
  3. Acidity
  4. Molarity
Show AnswerHide Answer

Correct answer: B

Atomicity

Atomicity is the number of atoms in a molecule.

Chemistry · Question 762

Which instrument accurately measures the masses of different isotopes?

  1. Mass spectrometer
  2. Infrared spectrometer
  3. Colorimeter
  4. Calorimeter
Show AnswerHide Answer

Correct answer: A

Mass spectrometer

A mass spectrometer separates ions and measures isotope mass-to-charge ratios.

Chemistry · Question 763

Positive isotope ions in a mass spectrometer are separated according to their:

  1. Mass only
  2. Charge only
  3. Mass-to-charge ratio
  4. Atomic volume
Show AnswerHide Answer

Correct answer: C

Mass-to-charge ratio

Their trajectories depend on m/z, the mass-to-charge ratio.

Chemistry · Question 764

For a gas collected over water, how is the dry-gas pressure obtained from total pressure?

  1. Add water-vapour pressure
  2. Subtract water-vapour pressure
  3. Multiply by water-vapour pressure
  4. Ignore water vapour
Show AnswerHide Answer

Correct answer: B

Subtract water-vapour pressure

Dalton's law gives Pgas = Ptotal − Pwater vapour.

Chemistry · Question 765

Graham's law concerns the rate of:

  1. Gaseous diffusion or effusion
  2. Liquid boiling
  3. Solid melting
  4. Electrolysis
Show AnswerHide Answer

Correct answer: A

Gaseous diffusion or effusion

Graham's law relates gas diffusion/effusion rate inversely to the square root of molar mass.

Chemistry · Question 766

At constant pressure, the volume of a fixed amount of gas is directly proportional to absolute temperature. This is:

  1. Boyle's law
  2. Charles's law
  3. Avogadro's law
  4. Dalton's law
Show AnswerHide Answer

Correct answer: B

Charles's law

Charles's law states V ∝ T at constant pressure.

Chemistry · Question 767

Absolute zero is approximately:

  1. 0 °C
  2. −100 °C
  3. −273 °C
  4. −373 °C
Show AnswerHide Answer

Correct answer: C

−273 °C

Absolute zero is 0 K, equal to approximately −273.15 °C.

Chemistry · Question 768

The electronegativity difference between two bonded atoms is an indicator of which property of a covalent bond?

  1. polar nature
  2. non-polar nature
  3. strength
  4. nature
Show AnswerHide Answer

Correct answer: A

polar nature

The correct choice is polar nature.

Chemistry · Question 769

The equilibrium Constant is always written as a ratio of

  1. Reactants over products
  2. Products over reactants
  3. Product times Reactants
  4. None of these
Show AnswerHide Answer

Correct answer: B

Products over reactants

The correct choice is Products over reactants.

Chemistry · Question 770

What is the relative atomic mass of copper?

  1. 63.345amu
  2. 63.455amu
  3. 63.55 amu
  4. 63.456amu
Show AnswerHide Answer

Correct answer: C

63.55 amu

The correct choice is 63.55 amu.