An $n-p-n$ transistor can be considered to be equivalent to two diodes connected back-to-back. Which of the following figures is the correct one?

Which of the following statements is true regarding transistor configurations?

The phase difference between input and output voltages of a $CE$ (common emitter) amplifier circuit is........$^o$.

For a given transistor,if $\alpha = I_C / I_E = 0.96$,then the current gain $\beta$ is:

An $n-p-n$ transistor is connected in common-emitter configuration as shown in the figure. If the collector current is $5 \text{ mA}$,$V_{BE} = 0.6 \text{ V}$,$V_{CE} = 3 \text{ V}$,and the common-emitter current amplification factor $\beta = 50$,then the values of $R_1$ and $R_2$ are respectively.

The voltage gain and current gain of a transistor amplifier in common emitter configuration are respectively $150$ and $50$. If the resistance in the base circuit is $850 \Omega$, then the resistance in the collector circuit is: (in $\Omega$)