Here’s a set of multiple-choice questions (MCQs) for Class 11 Chemistry Chapter 1, “Some Basic Concepts of Chemistry.” These questions will help you assess your understanding of key concepts in this chapter.
Some Basic Concepts of Chemistry MCQs with Answers
1. Which of the following is NOT a fundamental principle of chemistry?
a) Law of conservation of mass.
b) Law of definite proportions.
c) Law of multiple proportions.
d) Law of constant volume.
Answer: (d) Law of constant volume.
2. What is the molar mass of glucose (C6H12O6)?
a) 180 g/mol.
b) 90 g/mol.
c) 360 g/mol.
d) 240 g/mol.
Answer: (a) 180 g/mol.
3. Which law states that a chemical compound always contains the same elements in the same proportion by mass?
a) Law of conservation of mass.
b) Law of definite proportions.
c) Law of multiple proportions.
d) Gay-Lussac’s law.
Answer: (b) Law of definite proportions.
4. What is the mole concept?
a) The number of molecules in 1 gram of any substance.
b) The number of grams of a substance equal to its molar mass.
c) The amount of substance that contains 6.022 x 1023 particles.
d) A unit of weight for measuring the mass of small objects.
Answer: (c) The amount of substance that contains 6.022 x 1023 particles.
5. Which of the following is the empirical formula of a compound with molecular formula C2H4O2?
a) CH2O
b) CH4O2
c) C2H4O2
d) C4H8O4
Answer: (a) CH2O
6. What is the percentage composition of carbon in carbon dioxide (CO2)?
a) 27.27%
b) 72.72%
c) 42.86%
d) 57.14%
Answer: (a) 27.27%
7. Which of the following is NOT a unit of measurement for the number of moles?
a) mol
b) mmol
c) kg
d) μmol
Answer: (c) kg
8. What is the mass of 1 mole of water (H2O)?
a) 18 g
b) 18 kg
c) 18 mg
d) 18 mg
Answer: (a) 18 g
9. Which of the following is NOT a unit of concentration?
a) Molarity
b) Molality
c) Mole fraction
d) Speed
Answer: (d) Speed
10. How many moles of NaCl are present in 58.5 g of NaCl?
a) 1 mole
b) 2 moles
c) 0.5 mole
d) 1.5 moles
Answer: (a) 1 mole
Some Basic Concepts of Chemistry Fill in the blank MCQs with Answers
1. A pure substance which contains only one type of atom is called ————–.
(a) An element
(b) a compound
(c) a solid
(d) a liquid
Ans: (a) An element
Solution: An element is made up of only one type of atom.
2. The smallest particle that can take part in chemical reactions is ————–.
(a) Atom
(b) molecule
(c) Both (a) and (b)
(d) none of these
Ans: (c) Both (a) and (b)
Solution: The smallest particle that can take part in chemical reactions is both an atom and a molecule.
3. Which of the following is a homogeneous mixture?
(a) Mixture of soil and water
(b) Sugar solution
(c) Mixture of sugar, salt and sand
(d) Iodised table salt
Ans: (b) Sugar solution
Solution: Sugar solution is a homogeneous mixture. A homogeneous mixture is a mixture in which the composition is uniform throughout the mixture
4. The significant figures in 0.00051 are ————–.
(a) 5
(b) 3
(c) 2
(d) 26
Ans: (c) 2
Solution: The significant figures in 0.00051 are 2.
5. Formation of CO and CO2 illustrates the law of ————–.
(a) Law of conservation of mass
(b) Law of Reciprocal proportion
(c) Law of Constant Proportion
(d) Law of Multiple Proportion
Ans: (d) Law of Multiple Proportion
Solution: If an element forms more than one compound with another element for a given mass of an element, masses of other elements are in the ratio of small whole numbers.
6. The number of significant figures in 6.02 x 1023 is ————–.
(a) 23
(b) 3
(c) 4
(d) 26
Ans: (b) 3
Solution: The number of significant figures in 6.02 x 1023 is 3
7. The prefix 1018 is ————–.
(a) giga
(b) exa
(c) kilo
(d) mega
Ans: (b) exa
Solution: The prefix 1018 is exa
8. The mass of an atom of carbon is ————–.
(a) 1g
(b) 1.99 x 10 -23 g
(c) 1/12 g
(d) 1.99 x 1023 g
Ans: (b) 1.99 x 10 -23 g
Solution: The mass of an atom of carbon is {12 / (6.02 x 10 23)} = 1.99 x 10 -23 g
9. A measured temperature on Fahrenheit scale is 200F. What will this reading be on the Celsius Scale?
(a) 40 ℃
(b) 94 ℃
(c) 93.3 ℃
(d) 30 ℃
Ans: (c) 93.3 ℃
Solution: The relationship between Fahrenheit and degree Celsius is: (0F) = 9/5 (oC) +32.
10. Which of the following pairs of gases contains the same number of molecules?
(a) 16 g of O2 and 14 g of N2
(b) 6 g of O2 and 22 g of CO2
(c) 28 g of N2 and 22 g of CO2
(d) 32 g of CO2 and 32g of N2
Ans: (a) 16 g of O2 and 14 g of N2
Solution: Divide the given mass by its molar mass to get moles, then multiply times 6.022×1023 to get the number of molecules.