The ratio of the density of oxygen nucleus $({}^{16}_{8}\text{O})$ and helium nucleus $({}^{4}_{2}\text{He})$ is

Electrical conductivity of insulators is

Which of the following statement is NOT correct in the case of LED?
(A) It is a heavily doped p-n junction diode.
(B) It emits light only when it is forward biased.
(C) It emits light only when it is reverse biased.
(D) The energy of the light emitted is equal to or slightly less than the energy gap of the semiconductor used.

In which of the logic gate the following statement is true? "The output is high when either of the inputs is high but not if both inputs are high"