The process of emission of electrons?from metal by UV rays is-
1). Photoelectric emission
2). Thermionic emission?
3). Secondary emission
4). Field emission
?In the nuclear reactors, moderators are used to
1). Slow down the neutrons
2). Generate neutrons?
3). Accelerate neutrons
4). Absorb the neutrons?
The method of age determination called "radioactive uranium dating" cannot be used to determine the age of
1). rocks
2). fossils and plant bodies?
3). the earth
4). ?minerals on earth?
The most penetrating radiation out of?the following is
1). X - rays
2). $alpha$ - rays
3). $beta$ - rays
4). $gamma$ - rays
The main source of enrgy in Sun is:
1). Nuclear fusion?
2). Nuclear fission?
3). Chemical reaction?
4). Mechanical energy?