Basic Concepts of Chemistry – Multiple Choice Questions (MCQs)

1. 13. What is the molecular formula of a compound if its empirical formula is CH2O and its molar mass is 180 g/mol?

   • A. C6H12O6
   • B. C5H10O5
   • C. C4H8O4
   • D. C3H6O3

2. 14. The branch of chemistry that deals with the study of carbon compounds is:

   • A. Organic Chemistry
   • B. Inorganic Chemistry
   • C. Physical Chemistry
   • D. Analytical Chemistry

3. 15. Which of the following is a physical change?

   • A. Burning of wood
   • B. Rusting of iron
   • C. Melting of ice
   • D. Digestion of food

4. 16. The sum of protons and neutrons in an atom is called:

   • A. Mass number
   • B. Atomic number
   • C. Electron number
   • D. Mole number

5. 17. Atoms of the same element having different mass numbers are called:

   • A. Isotopes
   • B. Isobars
   • C. Isotones
   • D. Isomers

6. 18. How many moles of methane (CH4) are required to produce 22 g of CO2 upon combustion?

   • A. 0.5 mol
   • B. 1 mol
   • C. 2 mol
   • D. 0.25 mol

7. 19. The volume occupied by 1 mole of any gas at STP (Standard Temperature and Pressure) is:

   • A. 22.4 L
   • B. 2.24 L
   • C. 1 L
   • D. 10 L

8. 20. What is the concentration of a solution containing 0.2 mol of solute in 500 mL of solution?

   • A. 0.4 M
   • B. 0.2 M
   • C. 0.1 M
   • D. 0.04 M

9. 21. Which of the following is an intensive property?

   • A. Temperature
   • B. Volume
   • C. Mass
   • D. Energy

10. 22. Which of the following is an extensive property?

    • A. Density
    • B. Boiling point
    • C. Pressure
    • D. Volume

11. 23. The limiting reagent in a chemical reaction is the reactant that:

    • A. Is consumed completely
    • B. Is present in excess
    • C. Is not consumed
    • D. Is a catalyst

12. 24. The number of atoms in 16 g of O2 is (Avogadro's number = 6.022 x 10^23):

    • A. 6.022 x 10^23
    • B. 3.011 x 10^23
    • C. 12.044 x 10^23
    • D. 6.022 x 10^22