Chapter 1: Some Basic Concepts of Chemistry — Online MCQ Test
CHEMISTRY · Grade 11 · CBSE(NCERT)
Practice Chapter 1: Some Basic Concepts of Chemistry with a free chapter-wise online MCQ test.
This chapter covers: Matter Chemical combination Mole concept Avogadro number Atomic mass Molecular mass Empirical formula Molecular formula Stoichiometry Limiting reagent.
AI-generated questions from basic to board-exam level, with instant results and explanations.
Chapter 1: Some Basic Concepts of Chemistry — Important Questions & Answers
Which of the following is considered a chemical combination of substances?
- A. A mixture of sand and iron filings
- B. Water formed from hydrogen and oxygen
- C. Air in a cylinder
- D. A solution of sugar in water
Answer: B. Water formed from hydrogen and oxygen
Water is a compound formed by chemical combination of hydrogen and oxygen in a fixed ratio. The other options are mixtures.
Water is a compound formed by chemical combination of hydrogen and oxygen in a fixed ratio. The other options are mixtures.
The SI unit of amount of substance is:
- A. gram
- B. litre
- C. mole
- D. molecule
Answer: C. mole
The mole is the SI unit used to express the amount of substance.
The mole is the SI unit used to express the amount of substance.
How many moles are present in 18 g of water?
- A. 0.5 mol
- B. 1 mol
- C. 2 mol
- D. 18 mol
Answer: B. 1 mol
Molar mass of water is 18 g mol^-1, so 18 g corresponds to 1 mole.
Molar mass of water is 18 g mol^-1, so 18 g corresponds to 1 mole.
A sample contains 1.2044 × 10^24 molecules of NH3. The number of moles present is:
- A. 0.5 mol
- B. 1 mol
- C. 2 mol
- D. 4 mol
Answer: C. 2 mol
Dividing by Avogadro number gives 1.2044 × 10^24 / 6.022 × 10^23 = 2 mol.
Dividing by Avogadro number gives 1.2044 × 10^24 / 6.022 × 10^23 = 2 mol.
A student says that 1 mole of any substance contains 6.022 × 10^23 grams of that substance. Which is the best evaluation?
- A. Correct for all substances
- B. Correct only for gases
- C. Incorrect; 1 mole contains 6.022 × 10^23 entities, not grams
- D. Correct only at STP
Answer: C. Incorrect; 1 mole contains 6.022 × 10^23 entities, not grams
One mole refers to the number of entities, while the mass in grams depends on the molar mass of the substance.
One mole refers to the number of entities, while the mass in grams depends on the molar mass of the substance.