State whether the following statement is true or false:
Non-metals react with acids to produce a salt and hydrogen gas.

$(a)$ When calcium metal is added to water,the gas evolved does not catch fire,but the same gas evolved on adding potassium metal to water catches fire. Explain why?
$(b)$ Name a metal for each case:
$(i)$ It displaces hydrogen gas from nitric acid.
$(ii)$ It does not react with any physical state of water.
$(iii)$ It does not react with cold as well as hot water but reacts with steam.

$Al_{2}O_{3(s)} + 2NaOH_{(aq)} \xrightarrow{\Delta} \dots + H_{2}O_{(l)}$

$A$ mixture of equal amounts of $H_2$ and $Cl_2$ gases in a gas jar produces white fumes in the absence of sunlight. What are these white fumes?

Name a non-metal which is lustrous and a metal which is non-lustrous.

What is formed when boiling sulfur reacts with dihydrogen gas?