A particle of mass M at rest decays into two masses m₁ and m₂ with non zero velocities. The ratio of de-Broglie wavelengths of the particles $\frac{{\mathrm{\lambda }}_1}{{\mathrm{\lambda }}_2}$ is

• $\frac{{\mathrm{m}}_2}{{\mathrm{m}}_1}$

• $\frac{{\mathrm{m}}_1}{{\mathrm{m}}_2}$

• $\frac{\sqrt{{\mathrm{m}}_1}}{\sqrt{{\mathrm{m}}_2}}$

• 1 : 1

For an electron in the second orbit of Bohr's hydrogen atom, the moment of linear momentum is

• $\mathrm{\pi h}$

• $2\mathrm{\pi h}$

• $\frac{\mathrm{h}}{\mathrm{\pi }}$

• $\frac{2\mathrm{h}}{\mathrm{\pi }}$

If elements with principal quantum number n > 4 were not allowed in nature, the number of possible elements would have been

• 32

• 60

• 64

• 4

In photoelectric effect, the number of electrons ejected per second is

• proportional to the wavelength of light

• proportional to the intensity of light

• proportional to the work function of the metal

• proportional to the frequency of light

Half-life of a radioactive substance is 20 minutes. The time between 20% and 80% decay will be

• 40 minutes

• 20 minutes

• 25 minutes

• 30 minutes

A hypothetical radioactive nucleus decays according to the following series.

${}_{72}{\mathrm{A}}^{180} \stackrel{\mathrm{\alpha }}{\to } {\mathrm{A}}_1 \stackrel{{\mathrm{\beta }}^{-}}{\to } {\mathrm{A}}_2 \stackrel{\mathrm{\alpha }}{\to } {\mathrm{A}}_3 \stackrel{\mathrm{\gamma }}{\to } {\mathrm{A}}_4$

If the mass number and atomic number of A are respectively 180 and 72. Then the atomic number and mass number of A will respectively be

• 69, 171

• 70, 172

• 68, 172

• 69, 172

Nucleus A is converted into C through the following reactions

         $$\begin{gathered} \mathrm{A} \underset{}{\to } \mathrm{B} + \mathrm{\alpha } [\mathrm{\alpha } - \mathrm{alpha} \mathrm{paricle}] \\ \mathrm{B} \underset{}{\to } \mathrm{C} + 2\mathrm{\beta } [\mathrm{\beta }-\mathrm{electron}], \mathrm{then} \end{gathered}$$

• A and B are isotopes

• A and C are isobars

• A and B are isobars

• A and C are isotopes

If m, m_n , and m_p are the masses of _ZX^A nucleus, neutron and proton respectively

• m = (A − Z)m_n + Zm_p

• m < (A − Z)m_n + Zm_p

• m > (A − Z)m_n + Zm_p

• m = (A − Z)m_p + Zm_n

59.

The electrical circuit used to get smooth DC output from a rectifier circuit is called

• filter

• oscillator

• logic gates

• amplifier

In the case of constants α and β of a transistor

• α = β

• β < 1, α > 1

• αβ = 1

• β > 1, α < 1