Describe what is meant by the internal energy of a substance.

In an experiment, a heater of power $35 W$ is used to warm $0.240 kg$ of a liquid in an uninsulated container. The graph shows the variation of the temperature of the liquid with time.

The liquid never reaches its boiling point. Suggest why the temperature of the liquid approaches a constant value.

The volume of air in a car tyre is about $1.50\times {10}^{-2} m^3$ at a temperature of $0.0 °C$ and  pressure $250 kPa$.

Calculate the number of molecules in the tyre( in no. of Molecules).

For one vessel if Information is as given below. Then What is the Pressure of the given vessel? (in Pa)

$Volume of the vessel\left(V\right) = 1.60\times {10}^{-2} m^3$

$Temperature\left(T\right) = 35 °C$

$n = 1.653 mol$

if the pressure of the vessel is decrease from 250 kPa to 230 kPa in course of 8 hours and the volume and the temperature remain constant.  What is the average rate of the molecule loss? (in molecules/sec)

$Volume of the vessel\left(V\right) = 1.60\times {10}^{-2} m^3$

$Temperature\left(T\right) = 35 °C$