What is resonance in an $LCR$ series circuit?

$A$ series $LCR$ circuit with $L=0.5 \text{ H}$ and $R=10 \Omega$ is connected to an $AC$ supply with $rms$ voltage and frequency equal to $200 \text{ V}$ and $\frac{150}{\pi} \text{ Hz}$, respectively. The magnitude of the capacitance is varied so that the current amplitude in the circuit becomes maximum. The $rms$ voltage difference across the inductor is (in $\text{ V}$)

Give the value of impedance in resonance condition.

The tuning circuit of a radio receiver has a resistance of $50\,\Omega$,an inductor of $10\,mH$ and a variable capacitor. $A$ $1\,MHz$ radio wave produces a potential difference of $0.1\,mV$. The value of the capacitor to produce resonance is.......$pF$ (Take $\pi^2 = 10$).

With the gradual increase in frequency of an $A.C.$ source,the impedance of an $LCR$ series circuit

Which of the following combinations should be selected for better tuning of an $L-C-R$ circuit used for communication?