Calculate the mass of Calcium that will contain the same number of atoms as are present in 3.2 gm of sulphur. [S = 32, Ca = 40]

Select the correct answer from A, B, C and D : The ratio between the number of molecules in 2 g of hydrogen and 32 g of oxygen is:

(A) 1 : 2

(B) 1 : 0.01

(C) 1 : 1

(D) 0.01 : 1

[H = 1, O = 16]

A gas cylinder contains 12 x 10²⁴ molecules of oxygen gas.

Calculate : the mass of O₂ present in the cylinder.

(ii) the volume of O₂ at S.T.P. present in the cylinder.

[O = 16] Avog. no. is 6 × 10²³

Calculate the number of gram atoms in 4.6 grams of sodium [Na = 23]