Which gas can be adsorbed on a metal and released when required?

Galvanisation is a method of protecting iron from rusting by coating with a thin layer of :

Which of the following substances is hygroscopic?

Reaction between $X$ and $Y$ forms compound $Z$. $X$ loses an electron and $Y$ gains an electron. Which of the following properties is not shown by $Z$?

Why can oxides of highly reactive metals not be reduced by carbon?

What is thermit reaction? How is it used to join the railway tracks or cracked machine parts?