Which of the following,in general,is a slow process?

$A$ $500 \Omega$ resistor connected to an external battery is placed inside a thermally insulated cylinder fitted with a frictionless piston. The cylinder contains an ideal gas. $A$ current $i$ of $200 \text{ mA}$ flows through the resistor as shown in the figure. The mass of the piston is $10 \text{ kg}$. Assuming $g = 10 \text{ m/s}^2$, the speed at which the piston will move upward, due to heat dissipated by the resistor, so that the temperature of the gas remains unchanged is (in $\text{ cm/s}$)

$Assertion :$ The isothermal curves intersect each other at a certain point.
$Reason :$ The isothermal change takes place slowly,so,the isothermal curves have very little slope.

$A$ sample of an ideal gas undergoes an isothermal expansion. If $dQ$,$dU$,and $dW$ represent the amount of heat supplied,the change in internal energy,and the work done respectively,then:

If an ideal gas is compressed isothermally,then:

An ideal gas is subjected to an isothermal expansion such that its volume changes from $V_i$ to $V_f$ and pressure from $P_i$ to $P_f$. The work done on the gas is: