NCERT Solutions

Calculate the mass per cent of different elements present in sodium sulphate (Na₂SO₄).

Determine the empirical formula of an oxide of iron, which has 69.9% iron and 30.1 % dioxygen by mass.

Calculate the mass of sodium acetate (CH₃COONa) required to make 500 mL of 0.375 molar aqueous solution. Molar mass of sodium acetate is 82.0245 g mol⁻¹.

Calculate the concentration of nitric acid in moles per litre in a sample which has a density, 1.41 g mL⁻¹ and the mass per cent of nitric acid in it being 69%.

How much copper can be obtained from 100 g of copper sulphate (CuSO₄)?

Determine the molecular formula of an oxide of iron, in which the mass per cent of iron and oxygen are 69.9 and 30.1, respectively.

Calculate the atomic mass (average) of chlorine using the following data:

What is the concentration of sugar (C₁₂H₂₂O₁₁) in mol L⁻¹ if its 20 g are dissolved in enough water to make a final volume up to 2 L?

If the density of methanol is 0.793 kg L⁻¹, what is its volume needed for making 2.5 L of its 0.25 M solution?

Pressure is determined as force per unit area of the surface. The SI unit of pressure, pascal is as shown below: 1 Pa = 1 Nm⁻² If mass of air at sea level is 1034 g cm⁻², calculate the pressure in pascal.

What is the SI unit of mass? How is it defined?

What do you mean by significant figures?

If the speed of light is $3.0 \times 10^8$ m s⁻¹, calculate the distance covered by light in 2.00 ns.

How are 0.50 mol Na₂CO₃ and 0.50 M Na₂CO₃ different?

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

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).

What will be the mass of one ¹²C atom in g?

Use the data given in the following table to calculate the molar mass of naturally occuring argon isotopes:

Calculate the number of atoms in each of the following (i) 52 moles of Ar (ii) 52 u of He (iii) 52 g of He.

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.

Calcium carbonate reacts with aqueous HCl to give CaCl₂ and CO₂ according to the reaction, CaCO₃(s) + 2 HCl(aq) → CaCl₂(aq) + CO₂(g) + H₂O(l) What mass of CaCO₃ is required to react completely with 25 mL of 0.75 M HCl?

Chlorine is prepared in the laboratory by treating manganese dioxide (MnO₂) with aqueous hydrochloric acid according to the reaction 4 HCl(aq) + MnO₂(s) → 2 H₂O(l) + MnCl₂(aq) + Cl₂(g) How many grams of HCl react with 5.0 g of manganese dioxide?