Question

how many molecules of water are present in the 1.65 gram of copper sulphate

Answer 1

$18g \: of \: water \: = 6.022 \: \times {10}^{23} \\ 1g \: of \: water \: = \frac{6.022 \times {10}^{23} }{18} \\ 1.65g \: of \: water \: = \frac{6.022 \times {10}^{23} }{15} \times 1.65 \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 5.52 \times {10}^{22}$