What is reverse saturation current in diode ? Why it is temperature dependent ?

Identify the semiconductor devices whose characteristics are given below, in the order $\left(\mathrm{a}\right),\mathrm{ }\left(\mathrm{b}\right),\mathrm{ }\left(\mathrm{c}\right),\mathrm{ }\left(\mathrm{d}\right)$:

In the following circuit diagram, the current through the battery is

The given circuit has two ideal diodes connected as shown in the figure below. The current flowing through the resistance $R_1$ will be

If the Ge diode in the circuit is reverse biased, the current through $2\mathrm{k\Omega }$ resistor

$Ge$ and $Si$ diodes start conducting at $0.3 V$ and $0.7 V$ respectively. In the following figure if $Ge$ diode connection are reversed, the value of $V_0$ changes by: (assume that the Ge diode has large breakdown voltage)

In the following circuit, the equivalent resistance between $A$ and $B$ is

The $V-I$ characteristic of a diode is shown in the figure. The ratio of forward to reverse bias resistance is: