A real capacitor behaves like an $RLC$ resonant circuit, with an equivalent series resistance $R$ and an equivalent series inductance $L$.
A given capacitor shall have the following values:
1. What is the impedance $Z_{RLC}$ of this real capacitor for $f_0=44 ~\rm MHz$? (Phase and magnitude)
The impedance is based on the resistance $R$ and the reactance $X_{LC}= {\rm j}\cdot (X_L - X_C)$: \begin{align*} \underline{Z}_{RLC} &= R + {\rm j}\cdot (X_L - X_C) \\ &= R + {\rm j}\cdot (\omega L - {{1}\over{\omega C}}) \\ &= R + {\rm j}\cdot (2\pi f \cdot L - {{1}\over{2\pi f \cdot C}}) \\ \end{align*}
The reactive part is \begin{align*} X_{LC} &= 2\pi f \cdot L - {{1}\over{2\pi f \cdot C}} \\ &= 2\pi 44 \cdot 10^{6} {~\rm MHz} \cdot 1.6 \cdot 10^{-9} {~\rm H} - {{1}\over{2\pi \cdot 10^{6} {~\rm MHz} \cdot 10 \cdot 10^{-9} {~\rm F}}} \\ &= +0.08062... ~\Omega \\ \end{align*}
To get the magnitude of the impedance $|\underline{Z}_{RLC}|$ one can use the Pythagorean Theorem: \begin{align*} |\underline{Z}_{RLC}| &= \sqrt{R^2 + X_{LC}^2} \\ &= \sqrt{(0.020~\Omega)^2 + ( 0.08062... ~\Omega )^2} \\ &= 0.0830 ... ~\Omega \\ \end{align*}
For the phase $\varphi$ the $\arctan$ can be applied: \begin{align*} \varphi &= \arctan \left( {{X_{LC}}\over{R}} \right) \\ &= \arctan \left( {{0.08062... ~\Omega}\over{0.020 ~\Omega}} \right) \\ &= 1.3276 ... \hat{=} +76° \\ \end{align*}
2. What is the resonance frequency $f_r$ for the given capacitor? What is the impedance in this case?
The impedance at resonance is purely the resistance.
3. For an application, the component shall be used in resonance on a supply of $5 ~\rm V$. What is the voltage on the ideal capacity $C$ in the shown circuit?
The voltage on the ideal capacity is the input voltage by the $Q$-factor increased: \begin{align*} U_C &= U_{\rm s} \cdot Q \\ &= U_{\rm s} \cdot \sqrt{ {{L}\over{C}} } \cdot {{1}\over{R}}\\ &= 5 {~\rm V} \cdot \sqrt{ {{ 1.6 \cdot 10^{-9} {~\rm H} }\over{ 10 \cdot 10^{-9} {~\rm F} }} } \cdot {{1}\over{0.020~\Omega}}\\ &= 100 ~\rm V \end{align*}