Question

Match the following:

Column I	Column II
(i) \[\ce{88 g of CO2}\]	(a) 0.25 mol
(ii) 6.022 × 1023 molecules of \[\ce{H2O}\]	(b) 2 mol
(iii) 5.6 litres of \[\ce{O2}\] at STP	(c) 1 mol
(iv) \[\ce{96 g of O2}\]	(d) 6.022 x 1023 molecules
(v) 1 mol of any gas	(e) 3 mol

Answer 1

Column I	Column II
(i) \[\ce{88 g of CO2}\]	(b) 2 mol
(ii) 6.022 × 1023 molecules of \[\ce{H2O}\]	(c) 1 mol
(iii) 5.6 litres of \[\ce{O2}\] at STP	(a) 0.25 mol
(iv) \[\ce{96 g of O2}\]	(e) 3 mol
(v) 1 mol of any gas	(d) 6.022 x 1023 molecules

Explanation:

(i) The number of moles is given by the following formula,

Moles = `"Mass"/"Molar mass"`  ......(1)

So, the number of moles of \[\ce{CO2}\] is calculated by using equation (1) as follows,

Moles of \[\ce{CO2}\] = `(88  g)/((44  g)/(mol)` = 2 mol

(ii) 1 mol of \[\ce{H2O}\] given `6.022 xx 10^23` molecules. So `6.022 xx 10^23` molecules contain 1 mil of \[\ce{H2O}\].

(iii) 1 mol of gas occupies 22.4 litres of \[\ce{O2}\]. For 5.6 litres of \[\ce{O2}\], the number of moles of oxygen gas is calculated as 

Moles of \[\ce{O2}\] = `(1  mol)/(22.4  L) xx 5.6  L` = 0.25 mol

(iv) The number of moles of \[\ce{O2}\] is calculated bu using equation (1) as follows,

 Moles of \[\ce{O2}\] = `(96  g)/((32  g)/(mol)` = 3 mol

(v) 1 mole of any gas contains `6.022 xx 10^23` molecules.