The atmosphere is a mixture of gasses.
The balanced equation for
Ca(OH)2 + H3PO4→ Ca3(PO4)2 + H2O is
3 Ca(OH)2 +2 H3PO4→ Ca3(Po4)2 + 6 H2O
3 moles of Ca(OH)2 reacted with 2 moles of H3PO4 to form 1 mole of Ca3(PO4)2 and 6 moles of H2O
It would have to be 40.0 only because it wouldn’t add up
Here is your answer
B. NaCl
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In option A. Na isn't present.
In option C. there are two atoms of Na
So, option B is correct
HOPE IT IS USEFUL
