1. Which is not true about radioactive materials?

a. They give off radiations continuously by themselves

b. They give off radiations causing blackening on films

c. They give off radiations only when they can absorb energy from the outside force

d. They give off radiations which can pass through body tissues

2. Nuclear radiations are dangerous to the human body because they

a. ionize cells

b. provide oxygen to the cells

c. remove water from the cells

d. produce poisonous substances in cells

3. Which of the following nuclear radiations can pass through magnetic field undflected?

a. alpha rays

b. beta rays

c. gamma rays

d. positron rays