Chemistry 12 Chapter 7 Exemplar Solutions the P Block Elements Part 1

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I. Multiple Choice Questions (Type-I)

Question 1:

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

(i) reduces to

(ii) is of violet colour

(iii) gets oxidised to

(iv) changes to

Answer: (iii)

Question 2:

In qualitative analysis when is passed through an aqueous solution of salt acidified with dil. , a black precipitate is obtained. On boiling the precipitate with dil. , it forms a solution of blue colour. Addition of excess of aqueous solution of ammonia to this solution gives _________.

(i) Deep blue precipitate of

(ii) Deep blue solution of

(iii) Deep blue solution of

(iv) Deep blue solution of

Answer: (ii)

Question 3:

In a cyclotrimetaphosphoric acid molecule, how many single and double bonds are present?

(i) 3 double bonds; 9 single bonds

(ii) 6 double bonds; 6 single bonds

(iii) 3 double bonds; 12 single bonds

(iv) Zero double bonds; 12 single bonds

Answer: (i)

Question 4:

Which of the following elements can be involved in bonding?

(i) Carbon

(ii) Nitrogen

(iii) Phosphorus

(iv) Boron

Answer: (iii)

Question 5:

Which of the following pairs of ions are isoelectronic and isostructural?

(i)

(ii)

(iii)

(iv)

Answer: (i)

Question 6:

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

(i)

(ii)

(iii)

(iv)

Answer: (i)

Question 7:

Bond dissociation enthalpy of bonds is given below. Which of the compounds will act as strongest reducing agent?

(i)

(ii)

(iii)

(iv)

Answer: (iv)

Question 8:

On heating with concentrated solution in an inert atmosphere of , white phosphorus gives a gas. Which of the following statement is incorrect about the gas?

(i) It is highly poisonous and has smell like rotten fish.

(ii) It’s solution in water decomposes in the presence of light.

(iii) It is more basic than .

(iv) It is less basic than .

Answer: (iii)

Question 9:

Which of the following acids forms three series of salts?

(i)

(ii)

(iii)

(iv)

Answer: (iii)

Question 10:

Strong reducing behaviour of is due to

(i) Low oxidation state of phosphorus

(ii) Presence of two –OH groups and one P–H bond

(iii) Presence of one –OH group and two P–H bonds

(iv) High electron gain enthalpy of phosphorus

Answer: (iii)

Question 11:

On heating lead nitrate forms oxides of nitrogen and lead. The oxides formed are ______.

(i)

(ii)

(iii)

(iv)

Answer: (ii)

Question 12:

Which of the following elements does not show allotropy?

(i) Nitrogen

(ii) Bismuth

(iii) Antimony

(iv) Arsenic

Answer: (i)