Answer:
Volume of hydrogen gas required for each volume of carbon dioxide is 3 times the volume of carbon dioxide gas.
Explanation:

Volume of the carbon dioxide gas = 
Temperature of the carbon dioxide gas = 
Pressure of the carbon dioxide gas = 
Moles of carbon dioxide gas = 
(ideal gas equation )
..[1]
Volume of the hydrogen gas = 
Temperature of the hydrogen gas = 
Pressure of the hydrogen gas = 
Moles of hydrogen gas = 
..[2]
According to reaction 1 mole of carbon dioxide reacts with 3 moles of hydrogen gas.


Using above value in [2]


Given, 


Volume of hydrogen gas = 3 × volume of carbon dioxide gas
Volume of hydrogen gas required for each volume of carbon dioxide is 3 times the volume of carbon dioxide gas.