Which of the following exhibits a haplontic life cycle?

$\int (1+x-x^{-1}) e^{x+x^{-1}} dx$ is equal to :

Consider the two following statements $A$ and $B$,and identify the correct choice given in the answers :
$(A)$ In photovoltaic cells the photoelectric current produced is not proportional to the intensity of incident light.
$(B)$ In gas-filled photoemissive cells,the velocity of photoelectrons depends on the wavelength of the incident radiation.

The number of roots of the equation $(81)^{\sin ^2 x} + (81)^{\cos ^2 x} = 30$ in the interval $[0, \pi]$ is equal to

$AB$ is an ionic solid. The ionic radii of $A^{+}$ and $B^{-}$ are respectively $r_c$ and $r_a$. Lattice energy of $AB$ is proportional to :

$A$ light wave enters from medium $1$ to medium $2$. Its velocity in the $2^{\text{nd}}$ medium is double that in the $1^{\text{st}}$ medium. For total internal reflection,the angle of incidence must be greater than ....... $^{\circ}$.