a
(A)  \(\begin{gathered}
  \lambda \,\, = \,\,\frac{{\text{h}}}{{{\text{mv}}}}\,\,\,\,\, = \frac{{6.6 \times {{10}^{ - 34}} \times {{10}^7}}}{{25 \times 6.6 \times {{10}^4}cm/\sec }}\,\,erg\,\,\sec \,\,\,\, = \,\,1 \times \frac{{{{10}^{ - 38}}}}{{25}} \times {10^7}\,\, \hfill \\
   = \,\,0.04 \times {10^{ - 38}}\,\,\,\, = \,0.04 \times {10^{ - 31}}\,cm\,\,\,\, = \,\,4.0 \times {10^{ - 33}}\,\,cm \hfill \\ 
\end{gathered} \)