Answer
(a) 1
(b) 2
(c) 3
(d) 1
Work Step by Step
(a) In one mole of NaCl, we have 1 mole of sodium.
(b) In one mole of Na$_2$SO$_4$, we have 2 moles of sodium.
(c) In one mole of Na$_3$PO$_4$, we have 3 moles of sodium.
(d) In one mole of NaNO$_3$, we have 1 mole of sodium.
