Suppose an alpha particle accelerated by a potential of V volt is allowed to collide with a nucleus of atomic number Z, then the distance of closest approach of alpha particle to the nucleus is _____.

(a)

\(14.4\frac { Z }{ V } \mathring { A } \)

(b)

\(14.4\frac { V }{ Z } \mathring { A } \)

(c)

\(1.44\frac { Z }{ V } \mathring { A } \)

(d)

\(1.44\frac { V }{ Z } \mathring { A } \)

The ratio of the wavelengths radiation emitted for the transition from n = 2 to n = 1 in Li⁺⁺, He⁺ and H is _____.

(a)

1:2:3

(b)

1:4:9

(c)

3:2:1

(d)

4:9:36

If the nuclear radius of ²⁷Al is 3.6 fermi, the approximate nuclear radius of ⁶⁴Cu, in femi is _____.

(a)

2:4

(b)

1.2

(c)

4.8

(d)

3.6

A radioactive nucleus (initial mass number A and atomic number Z) emits two α-particles and 2 positons. The ratio of number of neutrons to that of proton in the final nucleus will be _____.

(a)

\(\frac{A-Z-4}{Z-2}\)

(b)

\(\frac{A-Z-2}{Z-6}\)

(c)

\(\frac{A-Z-4}{Z-6}\)

(d)

\(\frac{A-Z-12}{Z-4}\)

A radiative element has N₀ number of nuclei at t = 0. The number of nuclei remaining after half of a half-life _____.(that is, at time t = \(\frac{1}{2}T_\frac{1}{2}\))

(a)

\(\frac{N_0}{2}\)

(b)

\(\frac{N_0}{\sqrt2}\)

(c)

\(\frac{N_0}{4}\)

(d)

\(\frac{N_0}{8}\)

Bohr's postulate is based on _______________.

(a)

conservation of linear momentum

(b)

quantisation of angular momentum

(c)

conservation of quantum frequency

(d)

none of these

The ground state energy of a hydrogen atom is 13.6 eV. The energy needed to ionize H₂ atom from its second excited state ______________.

(a)

1.51 eV

(b)

3.4 eV

(c)

13.6 eV

(d)

none

An alpha nucleus of energy 1/2 mv² bombards a heavy nuclear target of charge Ze. Then the distance of the closest approach for the alpha nucleus will be proportional to ____________.

(a)

v²

(b)

\(\frac{1}{m}\)

(c)

\(\frac{1}{v^$}\)

(d)

\(\frac{1}{Ze}\)

The fig. represents the observed intensity of X-rays emitted by an X-ray tube as a function of wavelength. The sharp peaks A and B denote ____________.
 

(a)

continuous spectrum

(b)

band spectrum

(c)

characteristic spectrum

(d)

white radiations

A beam of electron posses undeflected through mutually perpendicular electric and magnetic fields. If the electric field is switched off and the same magnetic field is maintained, the electrons move ______________.

(a)

in a circular orbit

(b)

along a parabolic path

(c)

along a straight line

(d)

in an elliptical orbit

For first-order X-ray diffraction, the wavelength in of the X-ray is equal to the lattice spacing at a glancing angle is _____________.

(a)

15°

(b)

60°

(c)

45°

(d)

30°

In the given nuclear fission reaction, 'X' denotes which particle?
₉₂U₂₃₅ + ₀n₁ ➝ ₅₆Ba¹⁴¹ + ₃₆Kr⁹² + 3X + Q

(a)

electron

(b)

α -particle

(c)

neutron

(d)

neutrino

Elements having atomic number greater than ______ are radioactive.

(a)

48

(b)

68

(c)

88

(d)

83

Gamma rays are extensively used to destroy __________ affected cells

(a)

Sickle-cell anaemia

(b)

Cancer

(c)

HIV

(d)

Polio virus

Irene Curie and F. Joliot discovered ______ in the year 1934.

(a)

natural radioactivity

(b)

fluorescence

(c)

artificial radioactivity

(d)

hydrogen bomb

Minimum size of a system in which at least 1 neutron is available for further fission is called __________

(a)

cut-off size

(b)

critical size

(c)

range of reactor

(d)

capability criteria

Pressurised heavy-water reactors in our country generally use _____ as fuel.

(a)

natural uranium oxide

(b)

radioactive phosphorous

(c)

titanium dioxide

(d)

plutonium

Graphite is used as a __________ in nuclear reactors.

(a)

moderator

(b)

coolant

(c)

detector

(d)

fuel

In a nuclear reactor, cadmium rods are used to _____________

(a)

speed up neutrons

(b)

slow down neutrons

(c)

absorb neutrons

(d)

remove heat

The explosion of hydrogen bomb is based on the principle of _________________.

(a)

uncontrolled fission reaction

(b)

nuclear fusion reaction

(c)

controlled fission

(d)

photo electric effect