Answer:

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Explanation:

Let us discuss each of the given reactions in detail.

(A)

P

H

3

+H

+

→PH

4

+

The hybridization of P remains the same, i.e., sp

3

hybridization.

In PH

3

, P atom contains 3 bond pairs of electrons and one lone PAIR of electrons.

In PH

4

+

, P atom contains 4 bond pairs of electrons.

(B)

B

F

3

+H

2

S→H

2

S→BF

3

The hybridization of B changes from sp

2

to sp

3

.

In BF

3

, B contains 3 bond pairs and zero lone pair of electrons.

In H

2

S→BF

3

, B contains 4 bond pairs of electrons and zero lone pair of electrons.

(C) H

3

B

O

3

→HBO

2

+H

2

O

The hybridization of B changes from sp

2

to sp.

In H

3

BO

3

, B contains THREE bond pairs of electrons and zero lone pairs of electrons.

In HBO

2

, B contains two bonding domains.

(D) 2H

Cl

O

2

→HClO+HClO

3

The hybridization changes from sp

3

to no hybridization.

In HClO

2

, Cl has 2 bonding domains and 2 lone pairs of electrons. It undergoes sp

3

hybridization.

In HClO

3

, Cl has 3 bond pairs of electrons and 1 lone pair of electrons and undergoes sp

3

hybridization.

Hence, the first and FOURTH reactions do not undergo any change in the hybridisation of the underlined atom