Chemistry Class 12 NCERT Solutions: Chapter 7 The p Block Elements Part 5

Download PDF of This Page (Size: 320K)

Q: 33. How are xenon fluorides , and obtained?

Answer:

, and are obtained by a direct reaction . The condition under which the reaction is carried out determines the product.

Q: 34. With what neutral molecule is isoelectronic? Is that molecule a Lewis base?

Answer:

is isoelectronic to . Also, both species contain electrons in all as shown.

Total electrons

In

acts like a Lewis base as it accepts electrons from to form .

Q: 35. How are prepared?

Answer:

(i) can be prepared in two ways as shown

(ii) can be prepared using

Q: 36. Arrange the following in the order of property indicated for each set:

(i) - increasing bond dissociation enthalpy

(ii) - increasing acid strength

(iii) − increasing base strength.

Answer:

(i) Bond dissociation energy usually decreases on moving down a group as the atomic size increases. However, the bond dissociation energy of is lower than that of and . This is due to the small atomic size of fluorine. Thus, the increasing order for bond dissociation energy among halogens is as follows:

(ii)

The bond dissociation energy of molecules where , decreases with an increase in the atomic size. Since bond is the weakest, is the strongest acid.

(iii)

On moving from nitrogen to bismuth, the size of the atom increases while the electron density on the atom decreases. Thus, the basic strength decreases.

Q: 37. Which one of the following does not exist?

(i)

(ii)

(iii)

(iv)

Answer:

does not exist.

Q: 38. Give the formula and describe the structure of a noble gas species which is isostructural with:

(i)

(ii)

(iii)

Answer:

(i) is isoelectronic with and has square planar geometry

Q 38 Isoelectronic and Square Planar Geometry

Q 38 Isoelectronic and Square Planar Geometry

Q 38 Isoelectronic and Square Planar Geometry

(ii) is isoelectronic to and has a linear stricture

Q 38 (ii) Isoelectronic and Linear Stricture

Q 38 (Ii) Isoelectronic and Linear Stricture

Q 38 (ii) Isoelectronic and Linear Stricture

(iii) is isostructural to and has a pyramidal molecular structure

Q 38 (iii) Isoelectronic and Pyramidal Molecular Stricture

Q 38 (Iii) Isoelectronic and Pyramidal Molecular Stricture

Q 38 (iii) Isoelectronic and Pyramidal Molecular Stricture