1

### JEE Main 2018 (Online) 15th April Evening Slot

In KO2, the nature of oxygen species and the oxydation state of oxygen atom are, respectively :
A
Oxide and $-$ 2
B
Superoxide and $-$ 1/2
C
Peroxide and $-$ 1/2
D
Superoxide and $-$ 1

## Explanation

KO2 is called potassium superoxide. Here O$_2^ -$ is the superoxide ion.

Oxidation state of K is +1 and let oxidation state of oxygent atom is = x

$\therefore\,\,\,$ 1 + 2(x) = 0

$\Rightarrow$$\,\,\,$ x = $-$ ${1 \over 2}$
2

### JEE Main 2018 (Online) 15th April Evening Slot

In XeO3F2, the number of bond pair(s), $\pi$-bond(s) and lone pair(s) on Xe atom respectively are :
A
5, 2, 0
B
4, 2, 2
C
5, 3, 0
D
4, 4, 0

## Explanation $\therefore\,\,\,$ Number of Bond pairs = 5

Number of $\pi$ bonds = 3

Number of lone pairs = 0
3

### JEE Main 2018 (Online) 16th April Morning Slot

Among the oxides of nitrogen : N2O3, N2O4 and N2O5; the molecule(s) having nitrogen-nitrogen bond is / are :
A
Only N2O5
B
N2O3 and N2O5
C
N2O4 and N2O5
D
N2O3 and N2O4

## Explanation $\therefore$   N2O3   and   N2O4   has   N $-$ N   bond.
4

### JEE Main 2018 (Online) 16th April Morning Slot

A group 13 element 'X' reacts with chlorine gas to produce a compound XCl3. XCl3 is electron deficient and easily reacts with NH3 to form Cl3X $\leftarrow$ NH3 adduct ; however, XCl3 does not dimerize X is :
A
B
B
Al
C
Ga
D
In

## Explanation Here BCl3 is electron deficient compound as B has 6 electrons. That is why it accept electron pair from NH3 to form an adduct. BCl3 does not form dimer like Al, Ga or In, because its electron deficiency is complemented by the formation of co-ordinate bond between lone pair of electron of chlorine and empty unhybridized P-orbital of boron forming P$\pi$ $-$ P$\pi$ bonding.