Which of the following is responsible for turning moist starch iodide paper blue when it is brought in contact with O₃?

1. Liberation of iodine

2. Liberation of O₂

3. Formation of alkali

4. All of these

Which of the following is in correct sequence in terms of acid nature?

1. HClO₂ < HClO₃ < HClO₄

2. H₃PO₄ < H₃PO₃ < H₃PO₂

3. CH₄ < NH₃ < H₂O < HF

4. All of the above.

Which halogen produces O₂ when combined with hot concentrated NaOH?

1. F₂

2. Cl₂

3. Br₂

4. l₂

Among chalcogen, the highest tendency to form ${\mathrm{X}}^{-2}\left(\mathrm{g}\right)$ ion is exhibited by

1. Oxygen

2. Sulphur

3. Tellurium

4. Selenium

Which one of the following is not a pseudo halide?

1. CNO^-

2. RCOO^-

3. OCN^-

4. ${\mathrm{N}}_3^{-}$

Hypo on treatment with l₂ gives:

1. Na₂SO₄

2. Na₂S₄O₆

3. Na₂SO₃

4. Na₂S

The van der Waals forces are greatest in

1. Neon

2. Argon

3. Krypton

4. Xenon

The number of \(\mathrm{S=O}\) bonds present in \(\mathrm{H}_2\mathrm{S}_2 \mathrm{O}_8\) is:

Which of the following statements is true?

1 SO₂ bleaches by reduction.

2 Cl₂ bleaches by oxidation.

3 O₃ bleaches by oxidation.

4 All of the above.

Hl cannot be prepared by the action of Kl and H₂SO₄ because 

1. Hl is a much weaker acid than H₂SO₄

2. Hl gets oxidized by H₂SO₄ to form l₂

3. H₂SO₄ is a dehydrating reagent.

4. Hl is less volatile than H₂SO₄