They are so small that they dont scatter light, Or never settle out
I think the answer is A or C sorry for not having that good of an answer
Answer:
I am not quite sure about it, i think it is because of the fact that mercury has weight, when it is filled with mercury, it will expand a little bit.
When potassium is added to water, the metal melts and floats. It moves around very quickly on the surface of the water. The hydrogen ignites instantly. The metal is also set on fire, with sparks and a lilac flame.
An example of a single replacement reaction occurs when potassium (K) reacts with water (H2O). A colorless solid compound named potassium hydroxide (KOH) forms, and hydrogen gas (H2) is set free.