The wave theory of light does not explain photoelectricity because

An observer heard the sound of thunder 5.8s after the lightning flash was seen. How far was he from the source? [Speed of sound in air = 330ms-1]

Which of the following substances undergoes sublimation?

Determine the value of x from the nuclear reaction below,

\(^{222}_{86}Rn\) → \(^{x}_{88}Ra\) + 2β + energy