What is the speed of beta radiation in comparison to light?

Beta radiation consists of beta particles, which are high-energy, high-speed electrons (or positrons). The speed of beta particles is significant, but it does not reach the speed of light.

The correct answer reflects that beta particles can travel at a substantial fraction of the speed of light, often around 90%. This is because, while they are very fast, they do not have the ability to reach or exceed the speed of light due to the limitations imposed by the theory of relativity.

Understanding this, the other choices present different fractions or measurements that don’t accurately portray the behavior of beta particles. The speeds specified in the incorrect options, such as 50% or 99% of the speed of light, either underestimate or overestimate the common speeds of beta radiation. Additionally, the speed of sound is considerably slower than the speed of light and thus irrelevant in this context, since it doesn’t apply to the characteristics of beta radiation.