Which method is used to collect $H_2$ gas in a gas jar in the laboratory?

An element $A$ is soft and can be cut with a knife. It is very reactive to air and cannot be kept open in air. It reacts vigorously with water. Identify the element from the following:

$A$ metal $M$ forms an oxide having the formula $M_{2}O_{3}$. It dissolves in both dilute sulphuric acid and dilute sodium hydroxide solution. Identify the metal and write the chemical equations for the reactions involved.

Non-metals form two types of oxides. Choose these two types from the following oxides:
$SO_2, NO_2, CO, H_2O, N_2O$

Which of the following methods is used for the concentration of ore?

Which mixture of two gases,taken in equal proportions in a gas jar,reacts in the presence of sunlight?