NCERT Solutions for Chapter: Atoms and Molecules, Exercise 6: Exercises

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

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

Calculate the molar mass of the following substances.
(a) Ethyne, ${\mathrm{C}}_2{\mathrm{H}}_2$
(b) Sulphur molecule, ${\mathrm{S}}_8$ 
(c) Phosphorus molecule, ${\mathrm{P}}_4$ (Atomic mass of Phosphorus = $31 \mathrm{u}$)
(d) Hydrochloric acid, $\mathrm{H}\mathrm{C}\mathrm{l}$
(e) Nitric acid, $\mathrm{H}\mathrm{N}{\mathrm{O}}_3$.

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 $\left(\mathrm{N}{\mathrm{a}}_2\mathrm{S}{\mathrm{O}}_3\right)$?

Convert into mole.
(a) $12 \mathrm{g}$ of oxygen gas
(b) $20 \mathrm{g}$ of water
(c) $22 \mathrm{g}$ of carbon dioxide.

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

Calculate the number of molecules of Sulphur $\left({\mathrm{S}}_8\right)$ present in $16 \mathrm{g}$ of solid sulphur (Avogadro number = $6.022\times {10}^{23}$).

Calculate the number of aluminium ions present in $0.051\mathrm{}\mathrm{g}$ of aluminium oxide. (Take avogadro number as $6.022\times {10}^{23}$)
(Hint: The mass of an ion is the same as that of an atom of the same element. Atomic mass $\mathrm{Al}=27 \mathrm{u}$)