What is the reason we prefer $A.C.$ voltage over $D.C.$ voltage for power transmission?

Assertion: Long distance power transmission is done at high voltage.
Reason: At high voltage supply, power losses are less.

In a series $LR$ circuit with $X_L = R$. Power factor is $P_1$. If a capacitor of capacitance $C$ with $X_c = X_L$ is added to the circuit the power factor becomes $P_2$. The ratio of $P_1$ to $P_2$ will be :

$A$ coil,a capacitor,and an $AC$ source of $rms$ voltage $24 \,V$ are connected in series. By varying the frequency of the source,a maximum $rms$ current of $6 \,A$ is observed. If the coil is connected to a battery of $emf$ $12 \,V$ and internal resistance $4 \,\Omega$,then the current through it in the steady state is......$A$

If the input voltage $V_i$ to the circuit below is given by $V_i(t) = A \cos (2 \pi f t)$ and the output voltage is given by $V_o(t) = B \cos (2 \pi f t + \phi)$,which one of the following four graphs best depicts the variation of $\phi$ versus $f$?

An $AC$ voltage source of $E = 150 \sin(100t)$ is used to run a device which offers a resistance of $20 \,\Omega$ and restricts the flow of current in one direction only. The $r.m.s.$ value of current in the circuit will be.....$A$