The top of a wave is called the wave crest.
I think that the answer is A because if you think about water for an example. When water turns into ice, it's still technically water, just the molecules are frozen. The water is physically changed. It could also see why you think it is B but I don't think so completely. It doesn't really make sense to me. So I'd choose A. It's definitely not C or D.
Answer:
Explanation:
In this case, according to the Periodic table
there is 1g of hydrogen per mole. As we know that dihydrogen (H2) has two hydrogen atoms per molecule. So,there will be 2*1g hydrogen per mole=2g dihydrogen per mole.
If there is 2g dihydrogen per mole,and we have 4g,then we know that there is 2 mole dihydrogen in 4g.And for hydrogen there is 4 moles in 4g of hydrogen
