Which of the following metals produces hydrogen gas on reacting with cold dilute nitric acid?

Consider the following reactions:
$Cs + O_2 \text{ (excess)} \rightarrow X$
$Na + O_2 \rightarrow Y$
Identify the correct statement about $X$ and $Y$.

The element whose salts cannot be detected by flame test is

Which one on reaction with $NaOH$ solution gives inflammable gas?

Explain how industrial production of sodium hydroxide is carried out by the Castner-Kellner cell.

Which of the following absorbs carbon dioxide and releases oxygen?