\(\begin{array}{ll} t =0 & 7\,g \\ t = t & 2\, g \end{array}\)
at constant volume
\(t =\frac{2.303}{ K } \log \frac{[ A ]_0}{[ A ]_{ t }}\)
\(=\frac{2 \cdot 303}{2 \cdot 011 \times 10^{-3}} \log \frac{7}{2}\)
\(=\frac{2 \cdot 303 \times 0 \cdot 544}{2 \cdot 011 \times 10^{-3}}\)
\(=622.989\)
\(\approx 623\)