Which of the following statement is correct?

The rest mass of the stable nucleus is less than the sum of the rest masses of its separated nucleons

The rest mass of the stable nucleus is greater than the sum of the rest masses of its separated nucleons

In nuclear fission, energy is released by fusion is of two nuclei of medium mass (approximate 100 amu )

Which among the following statements is not true?

Madam curie discovered natural radio activity

Solar power may be future source of power for cars

Development in medicine may increase average life expectancy

X -rays were discovered by Roentgen

Which of the following nuclear reactions is possible?

Np 93 239 ⟶ Pu 94 239 + β - + ν ¯

B 5 10 + He 2 4 ⟶ N 7 13 + H 1 1

Na 11 24 + H 1 1 ⟶ Ne 10 20 + He 2 4

N 7 11 + H 1 1 ⟶ C 6 12 + β - + ν ¯

E M B I B E

Physics Crash Course NEET>Chapter 20 - Atoms and Nuclei>Level 1>Q 9

EASY

NEET

IMPORTANT

Earn 100

In a laboratory experiment on emission from atomic hydrogen in a discharge tube, only a few lines are observed whereas many lines are present in the hydrogen spectrum of a star. This is because in a laboratory,

60% studentsanswered this correctly

Important Questions on Atoms and Nuclei

EASY

NEET

IMPORTANT

Physics Crash Course NEET>Chapter 20 - Atoms and Nuclei>Level 1>Q 10

Rydberg constant

R

is equal to

EASY

NEET

IMPORTANT

Physics Crash Course NEET>Chapter 20 - Atoms and Nuclei>Level 1>Q 11

Nucleus

A

decays into

B

with a decay constant

λ_{1}

and

B

further decays into

C

with a decay constant

λ_{2}

. Initially, at

t = 0

, the number of nuclei of

A

and

B

were

3 N_{0}

and

N_{0}

respectively. If at t = t₀ number of nuclei of

B

becomes constant and equal to

2 N_{0}

, then

EASY

NEET

IMPORTANT

Physics Crash Course NEET>Chapter 20 - Atoms and Nuclei>Level 1>Q 12

A parent nucleus

X

is decaying into daughter nucleus

Y

which in turn decays to

Z

. The half lives of

X

and

Y

are

4000 years

and

20 years

, respectively. In a certain sample, it is found that the number of

Y

nuclei hardly changes with time. If the number of

X

nuclei in the sample is

4 \times 10^{20}

, the number of

Y

nuclei present in it is,

EASY

NEET

IMPORTANT

Physics Crash Course NEET>Chapter 20 - Atoms and Nuclei>Level 1>Q 13

Two species of radioactive atoms are mixed in equal number. The disintegration of the first species is

λ

and of the second is

\frac{λ}{3}

. After a long time, the mixture will behave as a species with mean life of approximately,

EASY

NEET

IMPORTANT

Physics Crash Course NEET>Chapter 20 - Atoms and Nuclei>Level 1>Q 14

90 %

of a radioactive sample is left undecayed after time than elapsed. What percentage of the initial sample will decay in a total time

2 t

.

MEDIUM

NEET

IMPORTANT

Physics Crash Course NEET>Chapter 20 - Atoms and Nuclei>Level 1>Q 15

The half-life of

_{92}^{238} U

undergoing

α -

decay is

4.5 \times 10^{9}

years

. Calculate the activity of

1 g

sample of

_{92}^{238} U

. (Avogadro's number is

6.022 \times 10^{23}

)

MEDIUM

NEET

IMPORTANT

Physics Crash Course NEET>Chapter 20 - Atoms and Nuclei>Level 1>Q 16

A radioactive sample, at any instant, has its disintegration rate $5000 disintegration per minute$ . After

5 \min

, the rate is $1250 disintegration per minute$ . Then, the decay constant (per

\min

) is

MEDIUM

NEET

IMPORTANT

Physics Crash Course NEET>Chapter 20 - Atoms and Nuclei>Level 1>Q 17

The half-life of radioactive Radon is

3.8 days

. The time at the end of which

{(\frac{1}{20})}^{th}

of the Radon sample will remain undecayed is (given

\log_{10} e = 0.4343

)

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