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 721

Which alkaline-earth metal occurs naturally only as radioactive isotopes?

  1. Calcium
  2. Magnesium
  3. Barium
  4. Radium
Show AnswerHide Answer

Correct answer: D

Radium

Radium has no stable isotopes and is naturally radioactive.

Chemistry · Question 722

Which listed Group 2 metal is the strongest reducing agent?

  1. Beryllium
  2. Magnesium
  3. Calcium
  4. Strontium
Show AnswerHide Answer

Correct answer: D

Strontium

Reducing strength generally increases down Group 2 as electron loss becomes easier.

Chemistry · Question 723

What is the composition of dolomite?

  1. CaCO₃
  2. MgCO₃
  3. CaCO₃·MgCO₃
  4. CaSO₄·2H₂O
Show AnswerHide Answer

Correct answer: C

CaCO₃·MgCO₃

Dolomite is the double carbonate CaCO₃·MgCO₃, also written CaMg(CO₃)₂.

Chemistry · Question 724

Approximately how much gypsum is added to Portland cement?

  1. 10-15%
  2. 20-30%
  3. 30-40%
  4. 2-3%
Show AnswerHide Answer

Correct answer: D

2-3%

A small amount, commonly about 2-3%, is added to regulate setting.

Chemistry · Question 725

Which metal ion is present at the centre of chlorophyll?

  1. Calcium
  2. Magnesium
  3. Sodium
  4. Potassium
Show AnswerHide Answer

Correct answer: B

Magnesium

Chlorophyll contains a central magnesium ion.

Chemistry · Question 726

When magnesium burns in air, which products can form?

  1. MgO only
  2. MgCO₃ only
  3. Mg₃N₂ only
  4. MgO and Mg₃N₂
Show AnswerHide Answer

Correct answer: D

MgO and Mg₃N₂

Magnesium reacts mainly with oxygen to form MgO and also with nitrogen to form Mg₃N₂.

Chemistry · Question 727

Setting of plaster of Paris involves:

  1. Oxidation by oxygen
  2. Reaction with carbon dioxide
  3. Dehydration
  4. Hydration to form another hydrate
Show AnswerHide Answer

Correct answer: D

Hydration to form another hydrate

Plaster of Paris hydrates and recrystallizes as gypsum during setting.

Chemistry · Question 728

Which oxide is amphoteric?

  1. CaO
  2. BaO
  3. BeO
  4. MgO
Show AnswerHide Answer

Correct answer: C

BeO

BeO reacts with both acids and strong bases, so it is amphoteric.

Chemistry · Question 729

Which metal produces a dazzling white light in fireworks and flares?

  1. Calcium
  2. Magnesium
  3. Barium
  4. Strontium
Show AnswerHide Answer

Correct answer: B

Magnesium

Burning magnesium emits an intense white light.

Chemistry · Question 730

Which chloride forms polymeric chains in the solid state?

  1. SrCl₂
  2. BaCl₂
  3. MgCl₂
  4. BeCl₂
Show AnswerHide Answer

Correct answer: D

BeCl₂

Electron-deficient BeCl₂ forms chloride-bridged polymeric chains in the solid state.