The circuit shown contains a $12 \ V$ battery,a $4 \ \Omega$ resistor,and two branches in parallel,each containing an ideal diode and a resistor. Branch $1$ has diode $D_1$ and a $3 \ \Omega$ resistor,while branch $2$ has diode $D_2$ and a $2 \ \Omega$ resistor. Determine the total current flowing in the circuit. (in $A$)

Which of the following statements are correct for alkali metal compounds?
$(i)$ Superoxides are paramagnetic in nature.
$(ii)$ The basic strengths of hydroxides increase down the group.
$(iii)$ The conductivity of chlorides in their aqueous solutions decreases down the group.
$(iv)$ The basic nature of carbonates in aqueous solutions is due to cationic hydrolysis.

The locus of the point $z=x+iy$ satisfying $\left|\frac{z-2i}{z+2i}\right|=1$ is

$A$ six-faced unbiased die is thrown twice and the sum of the numbers appearing on the upper face is observed to be $7$. The probability that the number $3$ has appeared at least once is:

If $(2, 0)$ is the vertex and the $y$-axis is the directrix of a parabola,then its focus is

All but one of the following compounds react with aniline to give acetanilide. Which one does not?