Question

In a closed flask of 5 litres, 1.0 g of $H_2$ is heated from 300 to 600 K. Which statement is not correct?
(a) Pressure of the gas increases
(b) The rate of collision increases
(c) The number of moles of gas increases
(d) The energy of gaseous molecules increases

Answer 1

Hint: The pressure exerted by a gas (with a given mass and held at a fixed volume) changes directly with the absolute temperature of the gas, according to Gay-law. In other words, while the mass is constant and the volume is constant, the pressure produced by a gas is proportional to the temperature of the gas.

Complete step by step solution:
In the year 1808, French scientist Joseph Gay-Lussac formulated this rule. The following is the mathematical formulation of Gay-Lussac's law.
\[P\propto T\]
$\dfrac{P}{T}=k$
The pressure exerted by the gas is denoted by P.
T is the gas's absolute temperature, while k is the constant.
This rule holds because temperature is a measure of a substance's average kinetic energy; when a gas's kinetic energy rises, its particles smash with the container walls more quickly, increasing pressure.
It is to be noted that this equation is independent of mass
Now comes the real question.
Because the volume is constant and the mass of hydrogen gas is constant, the number of moles remains constant. When the temperature rises, the pressure rises with it. As a result, there will be more collisions between gaseous molecules, increasing the energy of the molecules.
It's easy to see how the pressure of a gas (maintained at constant volume) decreases as it cools, until the gas ultimately condenses and becomes a liquid.
Hence option C is the incorrect statement.

Note:
The law of combining volumes says that when gases combine, they produce a volume with a simple whole number ratio as long as the temperature and pressure of the interacting gases and their products stay constant. The combined gas law is made up of Gay-(Amontons') Lussac's law, Charles's law, and Boyle's law. The ideal gas law may be used to generalise these three gas laws, as well as Avogadro's law.