Which of the following is a Lewis acid?

The equation of the parabola with focus $(0, 0)$ and directrix $x + y = 4$ is

The lines $2x + 3y = 6$ and $2x + 3y = 8$ cut the $X$-axis at $A$ and $B$,respectively. $A$ line $L$ drawn through the point $(2, 2)$ meets the $X$-axis at $C$ in such a way that the abscissae of $A, B,$ and $C$ are in arithmetic progression. Then,the equation of the line $L$ is

The correct relation between the degree of freedom $f$ and the ratio of specific heat $\gamma$ is -

Molten $CuCl_2$ is electrolysed using platinum electrodes. The reaction occurring at the anode is:

If $A$ and $B$ are mutually exclusive events with $P(B) \neq 1$,then $P(A \mid \bar{B})$ is equal to (Here $\bar{B}$ is the complement of the event $B$)