Which of the following ions will cause hardness in the water sample?

(i) Ca²⁺

(ii) Na⁺

(iii) Cl^-

(iv) K⁺

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