1

### AIPMT 2001

The following quantum numbers are possible for how many orbitals :

n = 3, $l$ = 2, m = +2 ?
A
1
B
2
C
3
D
4

## Explanation

n = 3, l = 2, m = +2

It shows one of the five d-orbitals(3d)
2

### AIPMT 2001

Main axis of a diatomic molecule is z, molecular orbital px and py overlap to from which of the following orbitals.
A
$\pi$ molecular orbital
B
$\sigma$ molecular orbital
C
$\delta$ molecular orbital
D
No bond will form

## Explanation

For $\pi$ overlap, the lobes of the atomic orbitals are perpendicularto the line joining the nuclei.

Hence only sidewise overlapping takes place.
3

### AIPMT 2000

Isoelectronic species are
A
CO, CN$-$, NO+, C${_2^{2 - }}$
B
CO$-$, CN, NO,
C
$C_2^ -$
D
CO, CN, NO, C2

## Explanation

No. of electrons CO = CN- = NO+ = $C_2^{2 - }$ = 14, So these are isoelectronics.
4

### AIPMT 2000

For given energy, E = 3.03 $\times$ 10$-$19 Joules corresponding wavelength is (h = 6.626 $\times$ 10$-$34 J sec, c = 3 $\times$ 108 m/sec)
A
65.6 nm
B
6.56 nm
C
3.4 nm
D
656 nm

## Explanation

E = ${{hc} \over \lambda }$

$\Rightarrow \lambda$ = ${{6.6 \times {{10}^{ - 34}} \times 3 \times {{10}^8}} \over {3.03 \times {{10}^{ - 19}}}}$

= 656 nm