In which of the following reactions H₂O₂ acts as a reducing agent?
1. H₂O₂ + 2H⁺ + 2e^- $$\to$$ 2H₂O
2. H₂O₂ - 2e^- $$\to$$ O₂ + 2H⁺
3. H₂O₂ + 2e^- $$\to$$ 2OH^-
4. H₂O₂ + 2OH^- - 2e^- $$\to$$ O₂ + 2H₂O

For the estimation of nitrogen, 1.4 g of organic compound was digested by Kjeldahl method and the evolved ammonia was absorbed in 60 mL of M/10 sulphuric acid. The unreacted acid required 20 ml of M/10 sodium hydroxide for complete neutralization. The percentage of nitrogen in the compound is:

CsCl crystallises in body centred cubic lattice. If ‘a’ is its edge length then which of the following expressions is correct?

Consider separate solutions of 0.500 M C₂H₅OH(aq), 0.100 M Mg₃(PO₄)₂(aq), 0.250 M KBr(aq) and 0.125 M Na₃PO₄(aq) at 25^oC. Which statement is true about these solutions, assuming all salts to be strong electrolytes?