Question

A cycle tube has volume $2000c{m}^3$. Initially the tube is filled to 3/4th of its volume by air at pressure of $105N/m^2$. It is to be inflated to a pressure of $6\times {10}^{5}N/m^2$ under isothermal conditions. The number of strokes of pump, which gives $500c{m}^3$ air in each stroke, to inflate the tube is

• A. 21
• B. 12
• C. 42
• D. 11

Answer 1

Answer: (A)

21

In this problem, let us conserve total number of moles before and after,

$\left(6X{10}^5\right)\left(2000\right)=\left(105\right)\left(1500\right)+\left(101325\right)\left(500\right)n$

Where n is total number of strokes of pump.

Solving this equation given $n\approx 21$.