Chemistry Class-11: Chapter –11. The p-Block Elements Part – 3

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Question: 18

is used during polymerization of organo silicones because

(i) The chain length of organo silicone polymers can be controlled by adding

(ii) blocks the end terminal of silicone polymer

(iii) improves the quality and yield of the polymer

(iv) acts as a catalyst during polymerisation

Answer: (i), (ii)

Question: 19

Which of the following statements are correct?

(i) Fullerenes have dangling bonds

(ii) Fullerenes are cage-like molecules

(iii) Graphite is thermodynamically most stable allotrope of carbon

(iv) Graphite is slippery and hard and therefore used as a dry lubricant in machines

Answer: (ii), (iii)

Question: 20

Which of the following statements are correct. Answer on the basis of Fig.11.1.

Structure of compound

Structure of Compound

Structure of compound

(i) The two bridged hydrogen atoms and the two boron atoms lie in one plane;

(ii) Out of six B–H bonds two bonds can be described in terms of 3 Centre 2-electron bonds.

(iii) Out of six B-H bonds four B-H bonds can be described in terms of 3 Centre 2 electron bonds;

(iv) The four terminal B-H bonds are two Centre-two electron regular bonds.

Answer: (i), (ii), (iv)

Question: 21

Identify the correct resonance structures of carbon dioxide from the ones given below:

(i)

(ii)

(iii)

(iv)

Answer: (ii), (iv)

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