1

AIPMT 2000

When an electron does transition from n = 4 to n = 2, then emitted line spectrum will be
A
first line of Lyman series
B
second line of Balmer series
C
first line of Balmer series
D
second line of Paschen series.

Explanation

Jump to second orbit leads to Balmer series. The jump from 4th orbit shall give rise to second line of Balmer series.
2

AIPMT 2000

Nuclear fission is best explained by
A
liquid droplet theory
B
Yukawa $\pi$-meson theory
C
independent particle model of the nucleus
D
proton-proton cycle.

Explanation

According to liquid drop model of nucleus, an excited nucleus breaks into lighter nuclei just like an excited drop breaks into tiny drops.
3

AIPMT 2000

For the given reaction, the particle X is
$_6{C^{11}} \to {}_5{B^{11}} + {\beta ^ + } + X$
A
neutron
B
anti neutrino
C
neutrino
D
proton

Explanation

The particle X is neutrino.