Which of the following regions of transistors are,respectively,heavily doped and lightly doped?

If $X, Y$ and $Z$ are the sizes of the emitter,base and collector of a transistor respectively,then

In a common emitter transistor amplifier, an input signal of $10 \ mV$ is applied. Due to this signal, the change in base current is $50 \ \mu A$ and the corresponding change in collector current is $5 \ mA$. If the load resistance in the collector-emitter circuit is $5 \ k\Omega$, the change in output voltage will be ..... $V$.

$A$ transistor is operated in common-emitter configuration at $V_{CE} = 2\, V$ such that a change in the base current from $100\,\mu A$ to $200\,\mu A$ produces a change in the collector current from $5\, mA$ to $10\, mA$. The current gain is

In a common emitter amplifier of a transistor,if the ratio of the voltage gain and current amplification factor is $4$,then the ratio of the collector and base resistances is

$A$ common emitter transistor amplifier has a current gain of $50$. If the load resistance is $4 \ k\Omega$ and input resistance is $500 \ \Omega$, the voltage gain of the amplifier is