What happens when gunpowder is ignited within a firearm?

When gunpowder is ignited within a firearm, it undergoes rapid combustion, producing a large amount of gas. This gas expands quickly, creating high pressure within the confines of the firearm’s chamber and barrel. This pressure is what propels the bullet down the barrel and out of the firearm at high speed.

The other choices do not accurately describe the result of igniting gunpowder. For instance, the idea that gunpowder cools and solidifies does not apply, as the ignition process results in heat and expansion, not cooling. Generating smoke is a byproduct, but smoke alone does not describe the vital process of pressure creation that propels the bullet. Similarly, the concept that gunpowder evaporates without effect is incorrect, as the ignition of gunpowder is what initiates the entire firing process. Understanding this fundamental principle is crucial for safe firearm handling and operation.