Which among the following is a haloalkyne?

If $A$ and $B$ are events of a random experiment such that $P(A \cup B) = \frac{4}{5}$,$P(\bar{A} \cup \bar{B}) = \frac{7}{10}$ and $P(B) = \frac{2}{5}$,then $P(A)$ equals

Which of the following ray diagrams shows physically possible refraction?

If $T$ is the surface tension of a soap solution,the amount of work done in blowing a soap bubble from a diameter $D$ to $2D$ is (in $pi D^2T$)

When glucose reacts with bromine water,the main product is

The process requiring absorption of energy is