b
\(P  = ({h_1} - {h_2}) \times {\rho _{Hg}} \times g\)\( = (75 - 50) \times {10^{ - 2}} \times {\rho _{Hg}} \times g\) ......(i)

\(P =h \times {\rho _{air}} \times g\) ......(ii)

\(h \times {\rho _{air}} \times g = (75 - 50) \times {10^{ - 2}} \times {\rho _{Hg}} \times g\)

\(\therefore \;h = 25 \times {10^{ - 2}}\left( {\frac{{{\rho _{Hg}}}}{{{\rho _{air}}}}} \right)\)

\( = 25 \times {10^{ - 2}} \times {10^4} = 2500\,m\)

પર્વતની ઊંચાઇ = 2.5 km.