Ch 13. Nuclei

Question 1

X-rays are

Answer 1

Electromagnetic waves

Question 2

The nucleus of any atom is made up of

Answer 2

Proton And Neutron

Question 3

The unit of radioactivity is

Answer 3

Curie

Question 4

Which of the following has the highest penetrating power?

Answer 4

y-rays (gamma rays)

Question 5

The half life of a radioactive isotope (²¹⁰Bi) is 5 days. The fraction of the nuclei undecayed at the end of 20 days will be

Answer 5

1/16

Question 6

The function of moderator in nuclear reactor is to

Answer 6

Slow the speed of neutrons

Question 7

Which of the following represents the α-decay of
AZ X (A ke neeche Z aur X)

Answer 7

z X A ———– z-2 Y A-4 + ₂He⁴

z neeche, A oopar, z-2 neeche, A-4 oopar,

Question 8

Which of the following is not a fundamental particle?

Answer 8

α-particle

Question 9

The source of solar energy is

Answer 9

Nuclear fission

Question 10

The least stable nucleus is

Answer 10

₂He⁴

Question 11

Atomic number decrease with the emission of α-particles from the nucleus by

Answer 11

2

Question 12

Cathode rays are

Answer 12

Electrons

Question 13

Density of nucleus is about

Answer 13

2.29 × 10¹⁷ kg m⁻³

Question 14

Which of the relations is correct for radioactive atom?

Answer 14

Half life = 0.6931 average life

Question 15

β-rays are fast moving

Answer 15

Electrons

Question 16

1 amu is equal to

Answer 16

1.6 × 10⁻²⁷ kg

Question 17

γ-rays are similar to

Answer 17

X-rays

Question 18

Which of the following is correct for radioactive element?

Answer 18

T a = 1/λ

Neeche a

Question 19

Which of the following is not charged?

Answer 19

Photon

Question 20

The atomic number and mass number for a specimen are Z and A respectively. The number of neutrons in the atom will be

Answer 20

A - Z

Question 21

The quantities, which remain conserved in a nuclear reaction

Answer 21

Total charge, Angular momentum, Linear momentum

Ans - All of the above

Question 22

Which one of the following is charge less?

Answer 22

Photon particle

Question 23

Time during which the amount of radioactive substance becomes half of its initial amount is called

Answer 23

Half life

Question 24

β-rays are deflected in

Answer 24

Both magnetic and electric field

Question 25

Which one of the following has maximum penetrating power?

Answer 25

γ-rays

Question 26

The number of neutrons in an atom of ₉₀Th²³⁰ is

Answer 26

140

Question 27

Statement 1st : All nuclei are not a same size.

Statement 2nd : The size of nucleus depends on atomic mass.

Answer 27

Both the statements are true and statement 2nd is the correct explanation of statement 1st

Question 28

The relation between half-life time T₁/₂ and decay constant is

Answer 28

T₁/₂ = 0.693/λ

Question 29

Which of the following is correct for α-particle?

Answer 29

Helium nucleus

Question 30

Which of the following equations is correct?

Answer 30

²³⁸ U —- ²³⁴ Th + ⁴ He
⁹² ⁹⁰ ²

Question 31

Which of the following relations is correct for mass and energy?

Answer 31

mc² = E

Question 32

Statement 1st : Energy is released in nuclear fusion.

Statement 2nd : Total binding energy of the product is less than total binding energy of reactants in nuclear reaction for nuclear fusion.

Answer 32

Both the statements are true and statement 2nd is the correct explanation of statement 1st