A proton is converted to a neutron by

1.β^- emission

2.β⁺ emission

3. electron capture

Which of the statements given above are correct?

• (1) and (2) only 

• (2) and (3) only

• (1) and (3) only

• (1), (2) and (3)

172.

In Neptunium series

${}_{94}{}^{241}\mathrm{Pu}\to \mathrm{Am}\to \mathrm{Np}\to \mathrm{Pa}\to {}_{92}{}^{238}\mathrm{U},$ the order of radiation

• β,α,α,β

• β,β,α,α

• α,α,β,β

• α,β,α,β

What number of subshells are possible in n = 3 energy level?

• 7

• 8

• 9

• 6

Four different sets of quantum numbers for 4 electrons are given below:

e₁ = 4, 0, 0, -$\frac{1}{2}$

e₂ = 3, 1, 1, -$\frac{1}{2}$

e₃ = 3, 2, 2, +$\frac{1}{2}$

e₄ = 3, 0, 0, +$\frac{1}{2}$

The order of energy of e₁, e₂, e₃, e₄ is 

• e₁ > e₂ > e₃ > e₄

• e₄ > e₃ > e₂ > e₁

• e₃ > e₁ > e₂ > e₄

• e₂ > e₃ > e₄ > e₁

Which of the following nuclei is most unstable?

• ${}_{20}{}^{40}\mathrm{Ca}$

• ${}_{35}{}^{55}\mathrm{Mn}$

• ${}_{50}{}^{119}\mathrm{Sn}$

• ${}_{13}{}^{30}\mathrm{Al}$

Electron affinity is positive when

• O^- is formed from O

• O^2- is formed from O^-

• O⁺ is formed from O

• electron affinite is always a negative value

A particle 'A' moving with a certain velocity has the de-Broglie wavelength 1 Å. For a particle 'B' with mass 25% of 'A' and velocity 75% of 'A'. The de-Broglie wave length of 'B' will be

• 3 Å

• 5.33 Å

• 6.88 Å

• 0.68 Å

The ratio of de-Broglie wavelengths for electron accelerated through 200 V and 50 V is

• 1:2

• 2:1

• 3:10

• 10:3

The nuclear reaction, ${}_{13}{}^{27}\mathrm{Al} + {}_2{}^4\mathrm{He} \to {}_{14}{}^{30}\mathrm{Si} + {}_1{}^1\mathrm{H}$ is

• nuclear fusion

• nuclear fission

• nuclear transmutation

• artificial radioactivity

n/p ratio during positron decay

• increases

• decreases

• remains constant

• All of these