NEET Physics Radioactivity MCQs Set A

a) all of the above

b) spontaneous

c) self disintegration process

d) irreversible process

Answer: all of the above

Question: Beta rays emitted by a radioactive material are

a) charged particles emitted by nucleus

b) neutral particles

c) the electrons orbiting around the nucleus

d) electromagnetic radiations

Answer: charged particles emitted by nucleus

Question: Which of the following is not a mode of a radioactive decay ?

a) Fusion

b) Positron emission

c) Electron capture

d) Alpha decay

Answer: Fusion

Question:  The same radioactive nucleus may emit

a)

b)

c)

d) None of these

Answer:

Question: A radioactive material undergoes decay by ejecting electrons. The electron ejected in this process is

a) the electron from the decay of a neutron

b) the electron present in the nucleus

c) an orbital electron

d) None of these

Answer: the electron from the decay of a neutron

Question: The rate of disintegration at a given instant, is directly proportional to the number of atoms present at that instant. This is the statement of

a) law of radioactive decay

b) half life

c) law of radioactive transformation

d) group displacement law

Answer: law of radioactive decay

Question: Half life of radioactive element depends upon

a) nature of element

b) pressure

c) temperature

d) amount of element present

Answer:  nature of element

Question:

a)

b) fusion

c) fission

d) None of these

Answer:

Question:

a) antineutrino

b) neutrino

c) photon

d) graviton

Answer: antineutrino

Question: A radioactive substance has a half life of four months. Three fourth of the substance will decay in

a) eight months

b) three months

c) four months

d) twelve months

Answer: eight months

Question: They decay constant of radium is 4.28 × 10^–4 per year. Its half life will be

a) 1620 years

b) 1240 years

c) 2000 years

d) 63 years

Answer:  1620 years

Question:   A radioactive element forms its own isotope after 3 consecutive disintegrations. The particles emitted are

a)

b)

c)

d)  None of these

Answer:

Question:  N atoms of a radioactive substance emit na-particles per second. The half life of the radioactive substance is

a)

b)

c)

d)

Answer:

Question:  The half life of the radioactive substance is 40 days. The substance will disintegrate completely in

a) infinite time

b) 400 days

c) 40 days

d) 4000 days

Answer: infinite time

Question: A radioactive substance contains 10000 nuclei and its halflife period is 20 days. The number of nuclei present at the end of 10 days is

a) 7070

b) 9000

c) 8000

d) 7500

Answer: 7070