The correct answer is D. Becquerel showed that uranium gave off radioactivity, and the Curies discovered other radioactive elements.
Ball 4 because the higher the elevation is the greater the potential energy it has
It magnifies light received from distant objects.
A comet is the loose, icy body with a long, narrow orbit.
Comets are very small solar system body made mainly of ices mixed with smaller amounts of dust and rock. Most comets are not larger than a few kilometers across. The main body of the comet is called the nucleus, and it can contain water, methane, nitrogen and other ices. Their speeds vary depending on their orbits and where they are in it. The closer they are to the sun, the faster they are going.
