In order for the chain reaction of uranium fission to take place in a nuclear reactor, should A/B arising from these C/D/E reactions.

• A. accelerate

• B. slow down

• C. electrons

• D. protons

• E. neutrons

Which are real life uses of nuclear phenomena?

• nuclear power plant

• radiation therapy

• smoke detectors

• stars shining

• erupting volcano

 $T_{\frac{1}{2}}=$  

•  $1.44\ \tau$  

•  $0.693\ \tau$  

•  $\frac{1}{\lambda}$  

•  $\log_e\ 2\ \times\lambda$  

Radioactive material X has a half-life of 5 days. What is the number of days taken for the activity of X to reduce to 12.5% of its initial activity?

• 5 days

• 10 days

• 15 days

• 20 days

The amount of energy released from nuclear fission depends on the

I. critical mass

II. speed of light in vacuum

III. mass deficit

• I. and II. only

• I. and III. only

• II. and III. only

• All the answer is correct

The energy emitted by the Sun is produced as a result

• coal burning

• the reaction cycle in which we get the helium nuclei from hydrogen nuclei

• uranium nucleus fission reaction

• pass electrons from higher shells to lower ones

Isotopes of the same elements have different

• Number of neutrons in nucleus

• Number of protons in nucleus

Nuclear energy is energy released from a ______ during nuclear reactions

• fast-moving proton

• fast-moving neutron

• fast-moving electron

• nucleus

___________ is a process where an unstable nucleus becomes a more stable nucleus by emitting radioactive radiation

• radioactive decay

• half-life

• nuclear fission

• nuclear fusion

The radioactive parent elements are

• uranium, actinium, thorium

• actinium, thorium, plutonium

• uranium, thorium, neptune, plutonium

• uranium, actinium, thorium, neptune