Chemistry Class 11 NCERT Solutions: Chapter 11 the p Block Elements Part 9

Q: 32. Give one method for industrial preparation and one for laboratory preparation of Equation and Equation each.

Answer:

Caron dioxide

In the laboratory, Equation can be prepared by the action of dilute hydrochloric acid on calcium carbonate. The reaction involved is as follows:

Equation

Equation is commercially prepared by heating limestone. The reaction involved is as follows:

Equation

Caron monoxide

In the laboratory, CO is prepared by the dehydration of formic acid with conc. Equation , at 373 K. The reaction involved is as follows:

Equation

Equation is commercially prepared by passing steam over hot coke. The reaction involved is as

follows:

Equation

Q: 33. An aqueous solution of borax is

(A) Neutral

(B) Amphoteric

(C) Basic

(D) Acidic

Answer:

(C) Borax is a salt of a strong base ( Equation ) and a weak acid ( Equation ). It is, therefore, basic in nature.

Q: 34. Boric acid is polymeric due to

(A) Its acidic nature

(B) The Presence of Hydrogen bonds

(C) Its monobasic nature

(D) Its geometry

Answer:

(B) Boric acid is polymeric because of the presence of hydrogen bonds. In the given figure, the dotted lines represent hydrogen bonds.

Q: 35. The type of hybridisation of boron in diborane is

(A) Equation

(B) Equation

(C) Equation

(D) Equation

Answer:

(C) Boron in diborane is Equation hybridised.

Q: 36. Thermodynamically the most stable form of carbon is

(A) Diamond

(B) Graphite

(C) Fullerenes

(D) Coal

Answer:

(B) Graphite is thermodynamically the most stable form of carbon.

Q: 37. Elements of group 14

(A) Exhibit oxidation state of Equation only

(B) Exhibit oxidation state of Equation and Equation

(C) Form Equation and Equation ion

(D) Form Equation and Equation ions

Answer:

(B) The elements of group 14 have Equation valence electrons. Therefore, the oxidation state of the group is Equation . However, as a result of the inert pair effect, the lower oxidation state becomes more and more stable and the higher oxidation state becomes less stable. Therefore, this group exhibits Equation and Equation oxidation states.

Q_37_B_Table of Elements of Group 14 have 4 Valence Electrons

Group 14 Element

Oxidation State

C

+4

Si

+4

Ge, Sn, Pb

+2, +4

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