On addition of conc. H₂SO₄ to a chloride salt, colourless fumes are evolved but in case of iodide salt, violet fumes come out. This is because

1. H₂SO₄ reduces HI to I₂

2. HI is of violet colour

3. HI gets oxidised to I₂

4. HI changes to HIO₃

Affinity for hydrogen decreases in the group from fluorine to iodine. Which of the halogen acids should have highest bond dissociation enthalpy?

1. HF

2. HCl

3. HBr

4. HI

Bond dissociation enthalpy of E—H (E = element) bonds is given below. Which of the compounds will act as strongest reducing agent?

Compound                    $N{H}_3$              $P{H}_3$                 $As{H}_3$                 $Sb{H}_3$

${∆}_{diss}(E-H)/kJ mo{l}^{-1}$     389             322                  297                    255

1. $N{H}_3$

2. $P{H}_3$

3. $As{H}_3$

4. $Sb{H}_3$

On heating with concentrated NaOH solution in an inert atmosphere of CO₂, white phosphorus gives a gas.
Incorrect statements among the following about the gas is: 

Which of the following acids forms three series of salts?

1. H₃PO₂

2. H₃BO₃

3. H₃PO₄

4. H₃PO₃

Which of the following elements does not show allotropy?

1. Nitrogen

2. Bismuth

3. Antimony

4. Arsenic

Maximum covalency of nitrogen is ______________.

1. 3

2. 5

3. 4

4. 6

Which of the following statements is wrong?

1. Single N–N bond is stronger than the single P–P bond.

2. PH₃ can act as a ligand in the formation of coordination compound with transition elements.

3. NO₂ is paramagnetic in nature.

4. Covalency of nitrogen in N₂O₅ is four.

Elements of group-15 form compounds in +5 oxidation state. However, bismuth forms only one well characterised compound in +5 oxidation state. The compound is:

1. Bi₂O₅

2. BiF₅

3. BiCl₅

4. Bi₂S₅

On heating ammonium dichromate and barium azide separately we get

1. N₂ in both cases

2. N₂ with ammonium dichromate and NO with barium azide

3. N₂O with ammonium dichromate and N₂ with barium azide

4. N₂O with ammonium dichromate and NO₂ with barium azide