51.

v₁ is the frequency of the series limit of Lyman series, v₂ is the frequency of the first line of Lyman series and v₃ is the frequency of the series limit of the Balmer series. Then

• v₁ − v₂ = v₃

• v₁ = v₂ − v₃

• $\frac{1}{{\mathrm{v}}_2} = \frac{1}{{\mathrm{v}}_1} + \frac{1}{{\mathrm{v}}_3}$

• $\frac{1}{{\mathrm{v}}_1} = \frac{1}{{\mathrm{v}}_2} + \frac{1}{{\mathrm{v}}_3}$

Assume the graph of specific binding energy versus mass number is as shown in the figure. Using this graph, select the correct choice from the following.

• Fusion of two nuclei of mass number lying in the range of 100 < A < 200 will release energy

• Fusion of two nuclei of mass number lying in the range of 51 < A < 100 will release energy

• Fusion of two nuclei of mass number lying in the range of 1 < A < 50 will release energy

• Fission of the nucleus of mass number lying in the range of 100 < A < 200 will release energy when broken into two fragments

Pick out the correct statement from the following.

• Energy released per unit mass of the reactant is less in case of fusion reaction

• Packing fraction may be positive or may be negative

• Pu²³⁹ is not suitable for a fission reaction

• For stable nucleus, the specific binding energy is low

A radioactive sample S₁ having the activity A₁ has twice the number of nuclei as another sample S₂ of activity A₂. If A₁ = 2A₁, then the ratio of half-life of S₂ to the half-life of S₂ is

• 4

• 2

• 0.25

• 0.75

When a neutron is disintegrated to give a β-particle,

• a neutrino alone is emitted

• a proton and neutrino are emitted

• a proton alone is emitted

• a proton and an antineutrino are emitted

The forbidden energy gap in Ge is 0.72 eV, Given, hc = 12400 eV-$\stackrel{\circ }{\mathrm{A}}$ . The maximum wavelength of radiation that will generate electron hole pair is

• $172220 \stackrel{\circ }{\mathrm{A}}$

• $172.2 \stackrel{\circ }{\mathrm{A}}$

• $17222 \stackrel{\circ }{\mathrm{A}}$

• $1722 \stackrel{\circ }{\mathrm{A}}$

In a p-n junction diode not connected to any circuit

• the potential is the same everywhere

• the p-type side has a higher potential than the n-type side

• there is an electric field at the junction directed from the n-type side to p-type side

• there is an electric field at the junction directed from the p-type side to n-type side

In a given direction, the intensities of the scattered light by a scattering substance for two beams of light are in the ratio of 256 : 81. The ratio of the frequency of the first beam to the frequency of the second beam is

• 64 : 127

• 1 : 2

• 64 : 27

• None of these

Identify the logic operation performed by the circuit given here.

• OR

• NOR

• NOT

• NAND

The de-Broglie wavelength ofthe electron in the ground state of the hydrogen atom is (radius of the first orbit of hydrogen atom = 0.53 $\stackrel{\circ }{\mathrm{A}}$)

• $1.67 \stackrel{\circ }{\mathrm{A}}$

• $3.33 \stackrel{\circ }{\mathrm{A}}$

• $1.06 \stackrel{\circ }{\mathrm{A}}$

• $0.53 \stackrel{\circ }{\mathrm{A}}$