Class 9
Subject Chemistry
Chapter Atoms and Molecules
Assignment 02
Atoms and Molecules Class 9 MCQs Questions with Answers
Question 1.
The chemical symbol for nitrogen gas is
(a) Ni
(b) N2
(c) N+
(d) N
Answer
Answer: (b) N2
Question 2.
The chemical symbol for sodium is
(a) So
(b) Sd
(c) NA
(d) Na
Answer
Answer: (d) Na
Question 3.
Which of the following would weigh the highest?
(a) 0.2 mole of sucrose (C12H22O11)
(b) 2 moles of CO2
(c) 2 moles of CaCO3
(d) 10 moles of H2O
Answer
Answer: (c) 2 moles of CaCO3
Question 4.
Which of the following has maximum number of atoms?
(a) 18 g of H2O
(b) 18 g of O2
(c) 18 g of CO2
(d) 18 g of CO4
Answer
Answer: (d) 18 g of CO4
Question 5.
Which of the following correctly represents 360 g of water?
(i) 2 moles of H2O
(ii) 20 moles of water
(iii) 6.022 × 10²³ molecules of water
(iv) 1.2044 × 10²⁵ molecules of water
(a) (i)
(b) (i) and (iv)
(c) (ii) and (iii)
(d) (ii) and (iv)
Answer
Answer: (d) (ii) and (iv)
Question 6.
3.42 g of sucrose are dissolved in 18 g of water in a beaker. The number of oxygen atoms in the solution are
(a) 6.68 × 10²³
(b) 6.09 × 10²³
(c) 6.022 × 10²³
(d) 6.022 × 10²³
Answer
Answer: (a) 6.68 × 10²³
Question 7.
A change in the physical state can be brought about
(a) only when energy is given to the system
(b) only when energy is taken out from the system
(c) when energy is either given to, or taken out from the system
(d) without any energy change
Answer
Answer: (c) when energy is either given to, or taken out from the system
Question 8.
The relative molecular mass of Na2S2O3.5H2O is
(a) 250 amu
(b) 250 g
(c) 248 amu
(d) 248 g
Answer
Answer: (c) 248 amu
Question 9.
Which of the following has maximum number of atom?
(a) 18 g H2O
(b) 18 g of O2
(c) 18 g of CO2
(d) 18 g of CH4
Answer
Answer: (d) 18 g of CH4
Question 10.
Percentage of calcium in calcium carbonate is
(a) 40
(b) 30
(c) 48
(d) 36
Answer
Answer: (a) 40
Question 11.
Which has maximum number of molecules?
(a) 1 g of CO2
(b) 1 g of N2
(c) 1 g of H2
(d 1 g of CH4
Answer
Answer: (c) 1 g of H2
Question 12.
What mass of carbon dioxide (CO2) will contain 3.011 × 1023 molecules?
(a) 11.0 g
(b) 22.0 g
(c) 4.4 g
(d) 44.0 g
Answer
Answer: (b) 22.0 g
Question 13.
The value of Avogadro’s constant is:
(a) 6.0 × 10²⁴
(b) 6.01 × 10²²
(c) 6.022 × 10²³
(d) 6.022 × 10-²³
Answer
Answer: (c) 6.022 × 10²³
Question 14.
How many times an atom of sulphur is heavier than an atom of carbon?
(a) 32 times
(b) 12 times
(c) 8/3 times
(d) 12/32 times
Answer
Answer: (c) 8/3 times
Question 15.
The number of oxygen atoms in 4.4 g of CO2 is approx.
(a) 6 × 10²²
(b) 6
(c) 12 × 10²³
(d) 1.2 × 10²³
Answer
Answer: (d) 1.2 × 10²³
Question 16.
Which of the following represents 12 u?
(a) Mass of 1 hydrogen atom
(b) Mass of C-12 atom
(c) Mass of 0-16 atom
(d) 1/12th of mass of C-12 atom.
Answer
Answer: (d) 1/12th of mass of C-12 atom.
Question 17.
Which of the following would weigh the highest?
(a) 0.2 mole of sucrose (C12H22O11)
(b) 2 moles of CO2
(c) 2 moles of CaCO3
(d) 10 moles of H2O
Answer
Answer: (c) 2 moles of CaCO3
Question 18.
The molecule having an atomicity of 4 is:
(a) Sulphate molecule
(b) Ozone molecule
(c) Phosphorus molecule
(d) Methane molecule
Answer
Answer: (c) Phosphorus molecule
