Đáp án:
a) 30g
c) 30%
Giải thích các bước giải:
\(\begin{array}{l}
a)\\
mNaOH = m{\rm{dd}} \times C\% = 200 \times 15\% = 30g\\
c)\\
mNaOH\,trong\,{\rm{dd}}15\% = m{\rm{dd}} \times C\% = 200 \times 15\% = 30g\\
mNaOH\,trong\,{\rm{dd}}\,40\% = m{\rm{dd}} \times C\% = 300 \times 40\% = 120g\\
mNaOH = 30 + 120 = 150g\\
m{\rm{dd}} = 200 + 300 = 500g\\
C\% NaOH = \dfrac{{mct}}{{m{\rm{dd}}}} \times 100\% = \dfrac{{150}}{{500}} \times 100\% = 30\%
\end{array}\)
