Answer:
usually when a river, ocean or lake...etc becomes deeper is because of the weather the more hydrogen and oxygen atoms the more water :D and also gravitys pull thats pulling it deeper is another reason.
~batmans wife dun dun dun...
Answer:

Explanation:
We already know that the mass number of an atom is the sum of the number of protons and the number of neutrons.
So, the mass number of this isotope is;
Number of protons = 7
Number of neutrons = 8
Mass number = 7 + 8 = 15
Hence, the isotope is;

Molar mass Na2CO3 = 106 g/mole
Using dimensional analysis:
0.787 moles Na2CO3 x 106 g/mole Na2CO3 = g Na2CO3
Answer = 83.4 g Na2CO3