Question

Which of the following gases retards the rate of photosynthesis?

• A. $\mathrm{CO}$
• B. ${\mathrm{NO}}_2$
• C. ${\mathrm{CO}}_2$
• D. $\mathrm{CFC}$

Answer 1

The correct option is B

${\mathrm{NO}}_2$

The explanation for the correct answer.

(B) ${\mathrm{NO}}_2$

• ${\mathrm{NO}}_2$ when present in higher concentrations it causes deterioration of leaves.
• Due to this, the rate of photosynthesis decreases.
• ${\mathrm{NO}}_2$gas is produced when fossil fuels are burned, Nitrogen $\left({\mathrm{N}}_2\right)$ ${\mathrm{O}}_2$ is released which combines to form ${\mathrm{NO}}_2$ Nitric oxide$\left(\mathrm{NO}\right)$. $$\begin{gathered} {\mathrm{N}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2\mathrm{NO}\left(\mathrm{g}\right) \\ 2\mathrm{NO}\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{NO}}_2\left(\mathrm{g}\right) \end{gathered}$$
• Thus,${\mathrm{NO}}_2$ gas retards the rate of photosynthesis.

The explanation for the incorrect answer

(A) $\mathrm{CO}$

• $\mathrm{CO}$ has a good impact on the plant as it has a positive impact on seed germination.
• It also helps the plants in stomatal opening and closing and also the development of roots.

(C) ${\mathrm{CO}}_2$

• ${\mathrm{CO}}_2$ is the essential gas for the process of photosynthesis and thus it increases the rate of photosynthesis.
• Plants take in ${\mathrm{CO}}_2$ and in turn release ${\mathrm{O}}_2$ as which is essential for the survival of animals and human beings also.
• Photosynthesis is the process by which green plants make their own food with the help of Water, Carbon dioxide, and chlorophyll in presence of sunlight.
  $6{\mathrm{CO}}_2\left(\mathrm{g}\right)+6{\mathrm{H}}_2\mathrm{O}\left(\mathrm{aq}\right)\to {\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6\left(\mathrm{s}\right)+6{\mathrm{O}}_2\left(\mathrm{g}\right)$

(D) $\mathrm{CFC}$

• $\mathrm{CFC}$ is a gas responsible for Ozone depletion because of which plants develop many diseases.
• It is not harmful to the growth of plants.

Thus, ${\mathrm{NO}}_2$ gas retards the rate of photosynthesis. Option B is correct.