Question

20cc of ${\text{C}}{{\text{O}}_{\text{2}}}$ gas is passed over red hot coke. The volume of carbon monoxide evolved is:
A. 10cc
B. 20cc
C. 30cc
D. 40cc

Answer 1

Hint: We know that 1 mole atom occupies 22.4 liters at NTP, and for a diatomic gas, 1 mole atom occupies 11.2 liters at NTP, as 1 mole of ${{\text{O}}_{\text{2}}}$ contains 2 mole of O or we can also expressed as one mole of oxygen molecule contains two mole of oxygen atoms. 22.4 liter of carbon dioxide $\left( {{\text{C}}{{\text{O}}_{\text{2}}}} \right)$ gives $2 \times 22.4$ liter of carbon monoxide.

 Complete step by step answer:
As we know the reaction between carbon (C) and carbon dioxide $\left( {{\text{C}}{{\text{O}}_{\text{2}}}} \right)$ is as follows:
     ${\text{C}}{{\text{O}}_{\text{2}}}\left( g \right) + {\text{C}}\left( s \right) \to 2{\text{CO}}\left( g \right)$
In this reaction one mole of carbon dioxide gas reacts with one mole of carbon which is in solid state and forms two mole of carbon monoxide gas. We know that volume is proportional to the number of moles. Thus 20 cc of ${\text{C}}{{\text{O}}_{\text{2}}}$ gas will form $2 \times 20{\text{cc}} = 40{\text{cc}}$ of carbon monoxide gas. Therefore the volume of carbon dioxide gas is 40cc.

Hence the correct option is D.

Additional Information:
Gas molecules consist of a large number of minute particles. Gas molecules are so tiny that we can neglect their actual volume fraction of the total volume which is occupied by gas.

Note:
We know that volume is a measurement of substance and cubic centimeter (cc) is a unit of volume. In a three dimensional measurement we can measure volume as length which measures size in one dimensional and area which measures size in two dimensional.