Question

$4.0 g$ of caustic soda $( NaOH )$ (mol mass 40 ) contains same number of sodium ions as are present in-

• A. $10.6 \, g$ of $Na _{2} CO _{3}$ (mol. mass $\left.106\right)$
• B. $58.5\, g$ of $NaCl$ (Formula mass 58.5 )
• C. $100 \, ml$ of $0.5 M Na _{2} SO _{4}$ (Formula mass 142 )
• D. $1 \, mol$ of $NaNO _{3}$ (mol. mass $\left.85\right)$

Answer 1

Answer: (C)

$\frac{4}{40} \times N _{ A }=\frac{ N _{ A }}{10}$ atom

$0.5\, M \, Na _{2} SO _{4}$

$=\frac{0.5 \times 2}{100} \times N _{ A }=\frac{ N _{ A }}{10}$