1

### NEET 2016 Phase 1

Which one of the following orders is correct for the bond dissociation enthalpy of halogen molecules?
A
Br2 > I2 > F2 > Cl2
B
F2 > Cl2 > Br2 > I2
C
I2 > Br2 > Cl2 > F2
D
Cl2 > Br2 > F2 > I2

## Explanation

Bond dissociation enthalpy decreases as the bond distance increases from F2 to I2. This is due to increase in the size of the atom, on moving from F to I.

F – F bond dissociation enthalpy is smaller then Cl – Cl and even smaller than Br – Br. This is because F atom is very small and hence the three lone pairs of electrons on each F atom repel the bond pair holding the F-atoms in F2 molecules.

The order of bond dissociation enthalpy is :

Cl2 > Br2 > F2 > I2
2

### NEET 2016 Phase 1

When copper is heated with conc. HNO3 it produces
A
Cu(NO3)2, NO and NO2
B
Cu(NO3)2 and N2O
C
Cu(NO3)2 and NO2
D
Cu(NO3)2 and NO

## Explanation

Cu +4HNO3 (conc.) $\to$ Cu(NO3)2 + 2NO2 + 2H2O
3

### NEET 2016 Phase 1

Which is the correct statement for the given acids?
A
Phosphinic acid is a monoprotic acid while phosphonic acid is a diprotic acid.
B
Phosphinic acid is a diprotic acid while phosphonic acid is a monoprotic acid.
C
Both are diprotic acids.
D
Both are triprotic acids.

## Explanation

4

### NEET 2016 Phase 1

Match the compounds given in column I with the hybridisation and shape given in column II and mark the correct option

Column ${\rm I}$ Column ${\rm I}$${\rm I}$
(A) XeF6 (i) distorted octahedral
(B) XeO3 (ii) square planar
(C) XeOF4 (iii) pyramidal
(D) XeF4 (iv) square pyramidal
A
(A) $\to$ (iv);  (B) $\to$ (iii);  (C) $\to$ (i);  (D) $\to$ (ii)
B
(A) $\to$ (iv);  (B) $\to$ (i);  (C) $\to$ (ii);  (D) $\to$ (iii)
C
(A) $\to$ (i);  (B) $\to$ (iii);  (C) $\to$ (iv);  (D) $\to$ (ii)
D
(A) $\to$ (i);  (B) $\to$ (ii);  (C) $\to$ (iv);  (D) $\to$ (iii)