Exercises

Author:Jharkhand Board

Jharkhand Board Science Solutions for Exercises

Simple step-by-step solutions to Exercises questions of Atoms and Molecules from Science: Class IX. Also get 3D topic explainers, cheat sheets, and unlimited doubts solving on EMBIBE.

Questions from Exercises with Hints & Solutions

HARD
9th Jharkhand Board
IMPORTANT

Write the chemical formulae of the following:
(a) Magnesium chloride
(b) Calcium oxide
(c) Copper nitrate
(d) Aluminium chloride
(e) Calcium carbonate.

MEDIUM
9th Jharkhand Board
IMPORTANT

Give the names of the elements present in the following compounds.
(a) Quick lime
(b) Hydrogen bromide
(c) Baking powder
(d) Potassium sulphate.

MEDIUM
9th Jharkhand Board
IMPORTANT

Calculate the molar mass of the following substances.
(a) Ethyne, C2H2
(b) Sulphur molecule, S8 
(c) Phosphorus molecule, P4 (Atomic mass of Phosphorus = 31 u)
(d) Hydrochloric acid, HCl
(e) Nitric acid, HNO3.

HARD
9th Jharkhand Board
IMPORTANT

What is the mass of
(a) 1 mole of nitrogen atoms?
(b) 4 moles of aluminium atoms (Atomic mass of aluminium =27)?
(c) 10 moles of sodium sulphite Na2SO3?

HARD
9th Jharkhand Board
IMPORTANT

Convert into mole.
(a) 12 g of oxygen gas
(b) 20 g of water
(c) 22 g of carbon dioxide.

HARD
9th Jharkhand Board
IMPORTANT

What is the mass of:
(a) 0.2 mole of oxygen atoms?
(b) 0.5 mole of water molecules?

HARD
9th Jharkhand Board
IMPORTANT

Calculate the number of molecules of Sulphur S8 present in 16 g of solid sulphur (Avogadro number = 6.022×1023).

HARD
9th Jharkhand Board
IMPORTANT

Calculate the number of aluminium ions present in 0.051g of aluminium oxide. (Take avogadro number as 6.022×1023)
(Hint: The mass of an ion is the same as that of an atom of the same element. Atomic mass Al=27 u)