Element X belongs to period 2 and group 1 of the periodic table. State the formula of the chloride of the element X.

Anurag added dilute H₂SO₄ to a given sample X and heated the mixture. He observed that a gas was liberated which had a foul smell of rotten eggs and it turned moist lead acetate paper silvery black. Name the gas evolved in the above case.

28g of nitrogen and 44g of carbon dioxide at the same conditions of temperature and pressure occupy the same amount of space. What term describes such space occupied by any gas?

When copper reacts with a hot dilute solution, reddish-brown fumes are observed. Another compound, P, having the same anion that is present in the hot solution on heating, melts into a colourless liquid, releasing only oxygen gas without any coloured fumes. Identify P.