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CBSE

Subject

Physics

NEET Physics : Nuclei

Multiple Choice Questions

151.

A radioactive substance has activity 64 times higher than the required normal level. If T_1/2 = 2h, then the time, after which it should be possible to work with it, is:

16 h
6 h
10 h
12 h

152.

A radioactive substance contains 10000 nuclei and its half-life period is 20 days. The number of nuclei present at the end of 10 days is

7070
9000
8000
7500

153.

Nuclear fusion is common to the pairs :

thermonuclear reactor, uranium based nuclear reactor
energy production in sun, uranium-based nuclear reactor
energy production in sun, hydrogen bomb
the disintegration of heavy nuclei, hydrogen bomb

154.

For the stability of any nucleus:

binding energy per nucleon will be more
binding energy per nucleon will be less
no. of electrons will be more
none of these

155.

In nuclear reaction

${}_{72}^{180}X \overset{- α}{\to} Y \overset{- β}{\to} Z \overset{- α}{\to} A \overset{- γ}{\to} P$

the atomic mass and number of P are, respectively:

170,69
172,69
172,70
170,70

156.

A radioisotope has a half-life of 5 yr. The fraction of the atoms of this material that would decay in 15 yr will be

157.

If the half-life of any sample of a radioactive substance is 4 days, then the fraction of the sample will remain undecayed after 2 days, will be

$\sqrt{2}$
$\frac{1}{\sqrt{2}}$
$\frac{\sqrt{2} - 1}{\sqrt{2}}$
$\frac{1}{2}$

158.

In a mean life of radioactive sample :

about $\frac{1}{3}$ of substance disintegrates
about $\frac{2}{3}$ of substance disintegrates
about 90% of the substance disintegrates
almost all the substance disintegrates

159.

Which of the following nuclei is fissionable but not possible?

${}_{92}U^{235}$
${}_{92}U^{233}$
${}_{92}U^{238}$
${}_{94}{Pu}^{239}$

160.

A particle of mass m at rest decays into two particles of masses m₁ and m₂ having non zero velocities. The ratio of de-Broglie wavelengths of the particles $\frac{λ_{1}}{λ_{2}}$ is

m₁/m₂
m₂/m₁
1.0
$\sqrt{\frac{m_{2}}{m_{1}}}$

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