# Question #76a8d

##### 1 Answer

May 11, 2015

You'd need to add **10 mL** of hydrogen to that volume of air to reach a concentration of *300 ppm*.

A hydrogen concentration of **1 ppm** can be expressed as the ratio between

This means that you can get the concentration in ppm by **multiplying** the ration between the volume of hydrogen and the volume of air by

In your case, a concentration of 300 ppm will require a volume of hydrogen equal to

Rounded to one sig fig, the number of sig figs given for 300 ppm, and expressed in mL, the answer will be