Question

Arrange the following in decreasing order of mass:
I. ${10}^{23}$ molecules of H${}_2$
II. 0.1 mol of H${}_2$O
III. 0.01 mole of atoms of Nitrogen
IV. 2.24 L of O${}_2$ at STP

• A. IV> II> I > III
• B. IV> I> II> III
• C. IV> III> I> II
• D. IV> I> III> II

Answer 1

The correct option is A IV> II> I > III

6.023 x 10${}^{23}$ molecules of H${}_2$ = 2 g
10${}^{23}$ molecules of H${}_2$ = 0.33 g
1 mol of H${}_2$O = 18 g
0.1 mol of H${}_2$O = 1.8 g
1 mol of N${}_2$ = 28 g
0.01 mol of N${}_2$ = 0.28 g
22.4 L of O${}_2$ at STP = 32 g
2.24 L of O${}_2$ at STP = 3.2 g
Thus the required order is
III < I < II < IV