“Mole Concept” MCQ with Answer Explanation : NEET 2025.

Here below some basic MCQ’s of “Mole Concept” with answer which is explained in details. Let’s check one by one which is given in below.

1. What does one mole of a substance contain?
   a) 6.022 × 10²³ molecules
   b) 1 gram
   c) 22.4 liters at STP
   d) All of the above

Answer: a) 6.022 × 10²³ molecules

Explanation: One mole, known as Avogadro’s number, corresponds to 6.022 × 10²³ entities, whether they are atoms, molecules, or ions.

2. Which of the following statements about the mole is true?
   a) The mass of one mole of any element is its atomic mass in grams.
   b) Moles are only applicable to gases.
   c) One mole of a gas occupies 10 liters at STP.
   d) Moles are a measure of volume.

Answer: a) The mass of one mole of any element is its atomic mass in grams.

Explanation: The atomic mass of an element (in grams) gives the mass of one mole of that element, which is fundamental to stoichiometry.

3. At standard temperature and pressure (STP), one mole of any ideal gas occupies:
   a) 22.4 L
   b) 24 L
   c) 1 L
   d) 1 m³

Answer: a) 22.4 L

Explanation: Under STP conditions, one mole of an ideal gas occupies 22.4 liters, a key concept in gas laws.

4. How many grams are in 0.5 moles of NaCl (Molar mass = 58.5 g/mol)?
   a) 29.25 g
   b) 58.5 g
   c) 117 g
   d) 14.625 g

Answer: a) 29.25 g

Explanation: To find the mass, multiply the number of moles by the molar mass: 0.5 moles × 58.5 g/mol = 29.25 g.

5. Which of the following represents the mole ratio in the reaction: 2H₂ + O₂ → 2H₂O?
   a) 1:2:2
   b) 2:1:2
   c) 2:2:1
   d) 1:1:1

Answer: b) 2:1:2

Explanation: The coefficients in the balanced equation represent the mole ratios of the reactants and products.

6. Which of the following is the correct definition of a mole?
   a) The mass of an object
   b) The amount of substance containing the same number of entities as there are atoms in 12 g of carbon-12
   c) A unit of pressure
   d) A measure of temperature

Answer: b) The amount of substance containing the same number of entities as there are atoms in 12 g of carbon-12

Explanation: A mole is defined based on Avogadro’s number, linking it to a specific quantity of carbon-12.

7. What is the molar mass of water (H₂O)?
   a) 18 g/mol
   b) 16 g/mol
   c) 20 g/mol
   d) 10 g/mol

Answer: a) 18 g/mol

Explanation: The molar mass of water is calculated by adding the masses of two hydrogen atoms (1 g/mol each) and one oxygen atom (16 g/mol).

8. How many moles are in 100 grams of Na (Molar mass = 23 g/mol)?
   a) 2.17 moles
   b) 4.35 moles
   c) 1.5 moles
   d) 3.5 moles

Answer: a) 4.35 moles

Explanation: To find the number of moles, divide the mass by the molar mass: 100 g ÷ 23 g/mol ≈ 4.35 moles.

9. In the reaction: 4Fe + 3O₂ → 2Fe₂O₃, what is the mole ratio of iron to oxygen?
   a) 1:1
   b) 2:3
   c) 4:3
   d) 3:4

Answer: c) 4:3

Explanation: The coefficients in the balanced equation show that 4 moles of iron react with 3 moles of oxygen.

10. Which of the following represents a conversion factor for moles to grams?
    a) Molar mass
    b) Avogadro’s number
    c) Density
    d) Temperature

Answer: a) Molar mass

Explanation: Molar mass is used to convert between the number of moles and the mass of a substance.