1

### IIT-JEE 2000 Screening

The electronic configuration of an element is 1s2, 2s2 2p6, 3s2 3p6 3d5, 4s1 This represents its
A
excited state
B
ground state
C
cationic form
D
anionic form
2

### IIT-JEE 2000 Screening

The number of nodal planes in a px orbital is
A
one
B
two
C
three
D
zero
3

### IIT-JEE 1999

The electrons, identified by quantum numbers n and l, (i) n = 4, l = 1, (ii) n = 4, l = 0, (iii) n = 3, l = 2 and (iv) n = 3, l = 1 can be placed in order of increasing energy, from the lowest to highest, as
A
(iv)<(ii)<(iii)<(i)
B
(ii)<(iv)<(i)<(iii)
C
(i)<(iii)<(ii)<(iv)
D
(iii)<(i)<(iv)<(ii)
4

### IIT-JEE 1998

ASSERTION:
Nuclide ${}_{13}^{30}Al$ is less stable than ${}_{20}^{40}Ca$

REASON:
Nuclides having odd number of protons and neutrons are generally unstable.
A
If both assertion and reason are correct, and reason is the correct explanation of the assertion.
B
If both assertion and reason are correct, and reason is not the correct explanation of the assertion.
C
If assertion is correct but reason is incorrect.
D
If assertion is incorrect but reason is correct.