The true statements about Charles' Law are:
A) For a fixed mass of gas, at a constant pressure, the volume (V) is directly proportional to the absolute temperature (T). This means that as the temperature increases, the volume of the gas also increases, assuming the pressure remains constant.
B) The volume of gas at the start is recorded as 30 cm3 with a temperature of 30°C. The cylinder is heated further till the thermometer records 60°C. The new volume of the gas is 32.97 cm3. This statement demonstrates the application of Charles' Law, as the increase in temperature leads to an increase in volume.
C) Heat energy is applied to a cylinder containing a specific volume of gas. The temperature of the gas increases. The average velocity of the gas particles increases resulting in an increase in the rate of collisions and the average force per collision. This produces a decrease in pressure inside the cylinder. This statement explains the underlying mechanism of Charles' Law, which is that as the gas particles gain kinetic energy with increasing temperature, the pressure inside the container decreases due to increased collision frequency and force.
Therefore, options A, B, and C are the true statements about Charles' Law. Option E is incorrect as there is indeed a relationship between temperature and volume for gases, as described by Charles' Law. Option D is also incorrect as increasing the volume of a closed reaction container does not necessarily decrease thermal energy.