Question

Which one of the following have largest mass?

• A. 5.6 L $C{O}_2$ at STP
• B. 2 g $H_2$ gas
• C. $6\times {10}^{22}$ molecules of $H_2$ gas
• D. $1.0g$ - atom of He gas

Answer 1

The correct option is A 5.6 L $C{O}_2$ at STP

(A) At STP, 22.4 L of $C{O}_2=1$ mole $=44$ g.
At STP, 5.6 L of $C{O}_2=\frac{5.6}{22.4}$ mole $=44\times \frac{5.6}{22.4}=11$ g.
(B) Mass of $H_2$ gas $=2$ g
(C) $6\times {10}^{22}$ molecules of $H_2$ gas $=\frac{6\times {10}^{22}}{6\times {10}^{23}}=0.1$ moles $=0.1mol\times 2g/mol=0.2$ g.
(D) 1.0 g atom of $He$ gas $1.0gatom\times 4g/gatom=4.0$ g.
Hence, 5.6 L of $C{O}_2$ at STP have maximum mass.