Has 9 protons and 9 electrons in per atom.........
Answer: A wave
Explanation:
Because it’s the one that’s cause the new medium to go between the two media.
Answer: Option (4) is the correct answer.
Explanation:
When sulfuric acid reacts with calcium hydroxide then it results in the formation of calcium sulfate and water.
The chemical reaction for the same will be as follows.

Thus, we can conclude that
salt is produced when sulfuric acid and calcium hydroxide react completely.
I think its A. it cant be C or D b/c we are measuring the distance between Earth and Saturn, not the speed.