Observe the table and answer the following.
| Gas | % in inhaled air | % in exhaled air |
| Oxygen | 21.00 | 16 |
| CO2 | 0.03 | 4 |
| Nitrogen | 78 | 78 |
(i)What has raised the % of CO2 in exhaled air ?
(ii) In the above table why is there no change in nitrogen percentage ?