Basic Concepts of Chemistry – Multiple Choice Questions (MCQs)

1. 1. Which of the following statements is true about a compound?

   • A. It can be separated into its constituents by physical methods
   • B. It has properties identical to its constituents
   • C. It has a fixed composition
   • D. It can be formed by mixing elements in any proportion

2. 2. What is the S.I. unit of amount of substance?

   • A. Mole
   • B. Kilogram
   • C. Gram
   • D. Liter

3. 3. 1 mole of any substance contains how many particles?

   • A. 6.022 x 10^23
   • B. 6.022 x 10^22
   • C. 6.022 x 10^24
   • D. 6.022 x 10^20

4. 4. The molar mass of H2O is approximately:

   • A. 18 g/mol
   • B. 16 g/mol
   • C. 2 g/mol
   • D. 1 g/mol

5. 5. What is the percentage of oxygen in H2O?

   • A. 88.89%
   • B. 11.11%
   • C. 50%
   • D. 75%

6. 6. Which law states that 'matter can neither be created nor destroyed'?

   • A. Law of Conservation of Mass
   • B. Law of Definite Proportions
   • C. Law of Multiple Proportions
   • D. Avogadro's Law

7. 7. Which of the following represents the empirical formula of glucose (C6H12O6)?

   • A. CH2O
   • B. C2H4O2
   • C. C3H6O3
   • D. C6H12O6

8. 8. How many grams of CO2 are produced by the complete combustion of 12 g of Carbon?

   • A. 44 g
   • B. 22 g
   • C. 12 g
   • D. 32 g

9. 9. The number of significant figures in 0.0050 is:

   • A. 2
   • B. 1
   • C. 3
   • D. 4

10. 10. Rounding off 18.35 to two significant figures gives:

    • A. 18
    • B. 18.4
    • C. 18.3
    • D. 19

11. 11. Which of the following is a homogeneous mixture?

    • A. Sand and water
    • B. Oil and water
    • C. Air
    • D. Iron filings and sulfur

12. 12. The number of atoms in 0.5 mole of nitrogen gas (N2) is:

    • A. 6.022 x 10^23
    • B. 3.011 x 10^23
    • C. 1.2044 x 10^24
    • D. 6.022 x 10^22