When a manganous salt is fused with a mixture of KNO₃ and solid NaOH, the oxidation number of Mn changes from +2 to

• +4

• +3

• +6

• +7

The reaction that takes place when Cl₂ gas is  passed through conc. NaOH solution is

• oxidation

• reduction

• displacement

• disproportionation

The brown complex obtained in the detection of nitrate radical is formulated as [Fe(H₂O)₅NO]SO₄. What is the oxidation number of Fe in this complex?

• +1

• +2

• +3

• 0

The oxidation state of C in C₆H₁₂O₆ is

• +6

• -6

• 0

• +4

Excess of KI reacts with CuSO₄ solution and then Na₂S₂O₃ solution is added to it. Which of the statements is incorrect for this reaction ?

• Cu₂I₂ is formed

• CuI₂ is formed

• Na₂S₂O₃ is oxidised

• Evolved I₂ is reduced

The oxidation number of carbon in CH₂O is:

• -2

• +2

• 0

• +4

Which of the following reaction involves oxidation and reduction?

• NaBr + HCl → NaCl + HBr

• HBr + AgNO₃ → AgBr + HNO₃

• H₂ + Br₂ → 2HBr

• Na₂O + H₂SO₄ → Na₂SO₄ + H₂O

Which of the following reactions are disproportionation reaction?

(a) 2Cu⁺ → Cu²⁺ + Cu⁰

(b) 3MnO${}_4^{2-} + 4{\mathrm{H}}^{+} \to 2{\mathrm{MnO}}_4^{-} + {\mathrm{MnO}}_2 + 2{\mathrm{H}}_2\mathrm{O}$

(c) 2KMnO₄ $\stackrel{∆}{\to } {\mathrm{K}}_2{\mathrm{MnO}}_4 + {\mathrm{MnO}}_2 + {\mathrm{O}}_2$

(d) 2MnO${}_4^{-} + 3{\mathrm{Mn}}^{2+} + 2{\mathrm{H}}_2\mathrm{O} \to 5{\mathrm{MnO}}_2 + 4{\mathrm{H}}^{\oplus }$

Select the correct option from the following

• (a), (b) and (c)

• (a), (c) and (d)

• (a) and (d) only

• (a) and (b) only