How many electrodes are in the tetrode?

In a triode valve,which of the following statements is correct?

$A$ triode whose mutual conductance is $2.5 \text{ mA/V}$ and anode resistance is $20 \text{ k}\Omega$,is used as an amplifier whose amplification factor is $10$. The load resistance connected in the plate circuit will be.....$\text{k}\Omega$.

$A$ triode has a transconductance $(g_m)$ of $2.5 \text{ mA/V}$ and an anode resistance $(r_p)$ of $20 \text{ k}\Omega$. If it is used as an amplifier with an amplification factor of $10$, what is the load resistance $(R_L)$ connected to the plate circuit in $\text{k}\Omega$?

$A$ triode has a mutual conductance of $2 \times 10^{-3} \text{ mho}$ and an amplification factor of $50$. The anode is connected through a resistance of $25 \times 10^3 \, \Omega$ to a $250 \, \text{V}$ supply. The voltage gain of this amplifier is

Before the saturation state of a diode,at plate voltages of $400 \, V$ and $200 \, V$,the currents are $i_1$ and $i_2$ respectively. The ratio $i_1/i_2$ will be: