Chapter 7: Atoms and Molecules — Online MCQ Test
SCIENCE · CLASS 10th · Tamil Nadu State Board
Practice Chapter 7: Atoms and Molecules with a free chapter-wise online MCQ test.
This chapter covers: This chapter covers atomic mass molecular mass Avogadro hypothesis and mole concepts. Students learn relative atomic mass calculation atomicity and gas volume relationships..
AI-generated questions from basic to board-exam level, with instant results and explanations.
Chapter 7: Atoms and Molecules — Important Questions & Answers
What is the standard reference used to calculate the relative atomic mass of an element?
- A. Carbon-12 isotope
- B. Hydrogen-1
- C. Oxygen-16
- D. Nitrogen-14
Answer: A. Carbon-12 isotope
The relative atomic mass is defined as the ratio of the average mass of one atom of an element to 1/12th of the mass of a carbon-12 atom.
The relative atomic mass is defined as the ratio of the average mass of one atom of an element to 1/12th of the mass of a carbon-12 atom.
The number of atoms present in one molecule of an element is known as its ________.
- A. Valency
- B. Atomicity
- C. Molarity
- D. Molecular mass
Answer: B. Atomicity
Atomicity is the number of atoms present in one molecule of an element.
Atomicity is the number of atoms present in one molecule of an element.
Calculate the molecular mass of Water (H2O). (Given: Atomic mass of H=1, O=16)
- A. 17 amu
- B. 18 amu
- C. 32 amu
- D. 34 amu
Answer: B. 18 amu
Molecular mass = (2 * 1) + (1 * 16) = 18 amu.
Molecular mass = (2 * 1) + (1 * 16) = 18 amu.
How many moles are there in 5.6 liters of Oxygen gas at STP?
- A. 0.25 moles
- B. 0.5 moles
- C. 1 mole
- D. 2 moles
Answer: A. 0.25 moles
Number of moles = Given volume / 22.4. So, 5.6 / 22.4 = 0.25 moles.
Number of moles = Given volume / 22.4. So, 5.6 / 22.4 = 0.25 moles.
An element X has a vapour density of 14. What is the atomicity of the element if its atomic mass is 7?
- A. 2
- B. 3
- C. 4
- D. 1
Answer: C. 4
Molecular mass = 2 * Vapour density = 28. Atomicity = Molecular mass / Atomic mass = 28 / 7 = 4.
Molecular mass = 2 * Vapour density = 28. Atomicity = Molecular mass / Atomic mass = 28 / 7 = 4.