Which of the following reaction involves oxidation and reduction ?

• NaBr + HCl $\to$ NaCl + HBr

• HBr + AgNO₃ $\to$ AgBr + HNO₃

• H₂ + Br₂ $\to$ 2HBr

• Na₂O + H₂SO₄ $\to$ Na₂SO₄ + H₂O

What is the oxidation number of chlorine in ClO₃^- ?

• + 5

• + 3

• + 4

• + 2

How many electrons are involved in oxidation of KMnO₄ in basic medium ?

• 1

• 2

• 5

• 3

Assertion : Ozone is a powerful oxidising agent in comparison to O₂.

Reason : Ozone is diamagnetic but O₂ is paramagnetic.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

135.

The ratio of Fe₂O₃ and Al, in thermite is :

• 1 : 3

• 1 : 2

• 3 : 1

• none of these

Which of the following reaction is a redox reaction ?

• P₂O₅ + 2H₂O $\to$ H₄P₂O₇

• 2AgNO₃ + BaCl₂ $\to$ 2AgCl + Ba(NO₃)₂

• BaCl₂ + H₂SO₄ $\to$ BaSO₄ + 2HCl

• Cu + 2AgNO₃ $\to$ Cu(NO₃)₂ + 2Ag

What is 'A' in the following reaction ?

2Fe³⁺(aq) + Sn²⁺(aq) $\mathrm{\to }$ 2Fe²⁺(aq) + A

• Sn³⁺(aq)

• Sn⁴⁺(aq)

• Sn²⁺(aq)

• Sn

Oxidation state of Fe in Fe₃O₄ is :

• 3/2

• 5/4

• 4/5

• 8/3

Assertion : Solution of Na₂CrO₄ in water is coloured.

Reason : Oxidation state of Cr in Na₂CrO₄ is +6.

• If both assertion and reason are true and the reason is the correct explanation of the assertion.

• If both assertion and reason are true and the reason is not the correct explanation of the assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

Assertion : PbI₄ is a stable compound.

Reason : Iodide stabilizes higher oxidation state.

• If both assertion and reason are true and the reason is the correct explanation of the assertion

• If both assertion and reason are true and the reason is not the correct explanation of the assertion

• If assertion is true but reason is false

• If both assertion and reason are false.