Radioactive elements emit α, β and γ rays and are characterised by their halflives. The radioactive isotope of hydrogen is

(i) Protium

(ii) Deuterium

(iii) Tritium  

(iv) Hydronium

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