Four statements about an atom are listed. 1 The atom has a nucleus surrounded by positively charged electrons. 2 Most of the atom is empty space. 3 The nucleus is positively charged. 4 The nucleus is very large compared with the rest of the atom. Which statements are correct?

When dealing with radioactive materials there are possible dangers. Which statement is correct?

An isotope X is radioactive and has a half-life of 4 years. A sample initially contains 8000 atoms of X. After how ma…

Energy is released in some power stations and in the Sun by either nuclear fission or nuclear fusion. Which type of n…

The speed of radio waves is c. A radio station transmits waves with a wavelength λ. What is the frequency of the tran…

Light is incident on a mirror and is reflected as shown. What is the angle of incidence and the angle of reflection?

Light is incident on one face of a glass block at an angle of incidence of 40°. The glass block is in air. The refrac…