Question

50 ml of hydrogen difuses out through a small hole from a vessel in 20 minutes.The time needed for 40 ml of oxygen to diffuse out is ___.

• A. 12 min
• B. 64 min
• C. 8 min
• D. 32 min

Answer 1

The correct option is B

64 min

If 40 ml $O_2$ will diffuse in t min ,so, $r_{O_2}=\frac{40}{t}$

$r_{H_2}=\frac{50}{20}\Rightarrow r_{O_2}=r_{H_2}\sqrt{\frac{M_{H_2}}{M_{O_2}}}=\frac{50}{20}\sqrt{\frac{2}{32}}=\frac{50}{20}\times \frac{1}{4}$

$\frac{40}{t}=\frac{50}{80}\therefore t=\frac{40\times 80}{50}=64min$