NCERT Questions – Basic Concepts

Q1. A compound contains 4.07% hydrogen, 24.27% carbon and 71.65% chlorine. Its molar mass is 98.96 g. What are its empirical and molecular formulas?

Q2. How many moles of methane are required to produce 22g (CO_2 (g)) after combustion?

Q3. 50.0 kg of (N_2 (g))(g) and 10.0 kg of (H_2 (g)) are mixed to produce (NH_3 (g)). Calculate the amount of (NH_3 (g)) formed.

Q4. The density of 3 M solution of NaCl is 1.25 (g mL^{–1}). Calculate the molality of the solution.

Q5. Calculate the molarity of NaOH in the solution prepared by dissolving its 4 g in enough water to form 250 mL of the solution.

Q6. Calculate the mass per cent of different elements present in sodium sulphate (Na_2SO_4 )

Q7. Calculate the mass of sodium acetate (CH_3COONa) required to make 500 mL of 0.375 molar aqueous solution. Molar mass of sodium acetate is 82.0245 g mol^{–1}.

Q8. If 10 volumes of dihydrogen gas reacts with five volumes of dioxygen gas, how many volumes of water vapour would be produced?

Q9. Calculate the molarity of a solution of ethanol in water, in which the mole fraction of ethanol is 0.040 (assume the density of water to be one).

Q10. A welding fuel gas contains carbon and hydrogen only. Burning a small sample of it in oxygen gives 3.38 g carbon dioxide, 0.690 g of water and no other products. A volume of 10.0 L (measured at STP) of this welding gas is found to weigh 11.6 g. Calculate (i) empirical formula, (ii) molar mass of the gas, and (iii) molecular formula.