1) State if the following are true or false- a) Radioactivity is the emission of tiny, invisible radio signals by the nuclei of certain atoms.

1)   State if the following are true or false-

a)    Radioactivity is the emission of tiny, invisible radio signals by the nuclei of certain atoms.

b)   When an atom emits an alpha particle, it becomes a different element.

c)    During beta decay, neutrons are converted to protons and electrons.

d)   A gamma ray is high energy photon.

e)    The hydrogen isotope known as tritium contains three neutrons.

f)    Nuclear power plants produce energy by fission reactions.

g)   The combination of two light nuclei to form a heavier one is known as nuclear fission.

2)   What is the missing particle (alpha, beta, gamma or positron) in each of the following-

a)    23190Th→ ____+ 23191Pa

b)   23190Th→ ____+22788Ra

c)    23190Th→ ____+23189Ac

3)   Complete the following nuclear reactions-

a)    23191Pa→_____ + 42He

b)   _____ →23495Am + 0-1e

4)   Write the complete nuclear fission reaction for U-235 and the nuclear fusion reaction employed in hydrogen bombs.

5)   Choose the correct option-

a)    Who discovered radioactivity?

i)Antoine Becquerel

ii) Pierre Curie

iii) Marie Curie

iv) Ernest Rutherford

v) Benjamin Franklin

b)   Which of the following types of radiations has the highest penetrating power?

i)alpha particles

ii) beta particles

iii) gamma particles

iv) positrons

v) none of the above

c)    The self amplifying reaction in which neutrons produced by the fission of one nucleus would induce fission in other nuclei is called

i)Critical mass

ii) Chain reaction

iii) Nuclear fusion

iv) Positron emission

v) none of the above 

d)   What happens to the atomic number of a nucleus that emits a beta particle?

i)It remains the same

ii) It increases by one.

iii) It decreases by one

iv) It increases by two

v) It decreases by two


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