To determine which of the given options is an alkaline gas, we should first understand the nature of each gas listed:
A. [tex]\( \text{NO}_2 \)[/tex] - Nitrogen dioxide: This is a reddish-brown gas with a sharp, biting odor. It is acidic in nature and is a strong oxidizing agent.
B. [tex]\( \text{NH}_3 \)[/tex] - Ammonia: This is a colorless gas with a pungent odor. It is known to be alkaline, meaning it has basic properties.
C. NO - Nitric oxide or nitrogen monoxide: This is a colorless gas that is relatively non-reactive and neutral in nature. It is neither acidic nor alkaline in typical conditions.
D. [tex]\( \text{N}_2\text{O} \)[/tex] - Nitrous oxide or laughing gas: This is a colorless gas with a slightly sweet odor. It has neutral properties and is not classified as either strongly acidic or alkaline.
E. [tex]\( \text{N}_2\text{O}_4 \)[/tex] - Dinitrogen tetroxide: This is a colorless or pale yellowish-brown gas that exists in equilibrium with nitrogen dioxide ([tex]\( \text{NO}_2 \)[/tex]). It tends to be acidic rather than alkaline.
Among these, the only gas that is known for its alkaline properties is ammonia ([tex]\( \text{NH}_3 \)[/tex]). Therefore, the correct answer is:
B [tex]\( \text{NH}_3 \)[/tex]
