According to Boyle's Law, when the volume of a gas in a sealed container decreases while the temperature remains constant, the pressure of the gas increases. This is because the gas particles are compressed into a smaller space, resulting in more collisions between the gas particles and the container walls. As a consequence, the force exerted by the gas particles on the container walls increases, leading to a higher pressure.

Mathematically, Boyle's Law can be expressed as:

P₁V₁ = P₂V₂

where:

P₁ is the initial pressure

V₁ is the initial volume

P₂ is the final pressure

V₂ is the final volume

In this case, since the volume decreases while the temperature stays constant, the relationship between the initial and final states can be described as:

P₁V₁ = P₂V₂

where:

P₁ is the initial pressure

V₁ is the initial volume (greater than V₂)

P₂ is the final pressure (greater than P₁)

V₂ is the final volume (smaller than V₁)

Therefore, the decrease in volume of a gas sealed in a container with no change in temperature results in an increase in the pressure of the gas.