$A$ bulb and a capacitor are connected in series to a source of alternating current. If its frequency is increased,while keeping the voltage of the source constant,then

Which of the following is correctly matched?

If $(1+x+x^2+x^3)^5 = \sum_{k=0}^{15} a_k x^k$,then $\sum_{k=0}^7 a_{2k}$ is equal to

Consider a $p-n$ junction as a capacitor,formed with $p$ and $n$-materials acting as thin metal electrodes and depletion layer width acting as separation between them. Basing on this,assume that an $n-p-n$ transistor is working as an amplifier in $CE$ configuration. If $C_1$ and $C_2$ are the base-emitter and collector-emitter junction capacitances,then :

$1\,kg$ of ice at $-10\,^{\circ}C$ is mixed with $4.4\,kg$ of water at $30\,^{\circ}C$. The final temperature of the mixture is ........ $^{\circ}C$ (specific heat of ice is $2100\,J/kg\cdot K$,latent heat of fusion of ice is $336000\,J/kg$,and specific heat of water is $4200\,J/kg\cdot K$).