Dihydrogen can be prepared on a commercial scale by different methods. In its preparation by the action of steam on hydrocarbons, a mixture of CO and H₂gas is formed. It is known as

(i) Water gas

(ii) Syngas

(iii) Producer gas

(iv) Industrial gas

H₂S has minimum boiling point.

PbS + 4H₂O_2->PbSO₄ + 4H₂O.

Volume strength of H₂O₂ = Molarity * 11.2

HF molecules are associated with strong intermolecular hydrogen bonding hence its boiling point is the highest

Compound             Melting Point (K)

HF                          190

HCl