9.87X1024 atoms (NH4) 3 PO4 = how many moles

16.4moles

Explanation:

From Avogadro's hypothesis, 1mole of any substance contains 6.02x10^23 atoms.

This clearly indicates that 1mole of (NH4) 3PO4 also contains 6.02x10^23 atoms.

Now, if 1mole of (NH4) 3PO4 contains 6.02x10^23 atoms,

Then Xmol of (NH4) 3PO4 will contain 9.87X10^24 atoms i. e

Xmol of (NH4) 3PO4 = 9.87X10^24/6.02x10^23 = 16.4moles