Answer :
[tex]C_{i}=\frac{n_{i}}{V}\\\\
n_{i}=\frac{m}{M_{NaCl}}\\\\
C_{i}=\frac{\frac{m}{M_{NaCl}}}{V}=\frac{m}{M_{NaCl}V}\\\\
m=10g\\
M_{NaCl}=58.5\frac{g}{mol}\\
V=100ml=0.1L\\\\
C_{i}=\frac{10g}{58.8\frac{g}{mol}*0.1L}=1.71\frac{mol}{L}[/tex]