Modern Physics ...

A radioactive atom X emits X-particle to produce an atom Y which then emits an X-particle to give an atom Z

1.   The atomic number of X is less than that of Z. 
2.   The atomic number of Y is less than that of Z
3.   The mass number of X is the same as that of Y

In photoelectric effect the maximum kinetic energy of ejected electrons is linearly proportional to the

A surface ejects electrons when illuminated by blue light but none with green light. Then photo emission is possible by light of which of the following colours

For photoelectric effect the shopping potential depends

A radioactive material decays by simultaneous emission of two particles with respective half-lives 1620 and 810 years. The time, in years, after which one-fourth of the material remains is