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

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

Answer:

Caron dioxide

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

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

Caron monoxide

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

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

follows:

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 ( ) and a weak acid ( ). 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 34 B Structure of Boric Acid

Q 34 B Structure of Boric Acid

Q 34 B Structure of Boric Acid

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

(A)

(B)

(C)

(D)

Answer:

(C) Boron in diborane is 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 only

(B) Exhibit oxidation state of and

(C) Form and ion

(D) Form and ions

Answer:

(B) The elements of group 14 have valence electrons. Therefore, the oxidation state of the group is . 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 and oxidation states.

Q_37_B_Table of Elements of Group 14 Have 4 Valence Electrons
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