Will the pendulum that keeps correct time at Karachi be accurate at the mount Everest?

No, the pendulum that keeps correct time at Karachi will not be accurate at Mount Everest due to differences in gravitational acceleration and altitude. The pendulum's timekeeping is influenced by gravity, which is weaker at higher elevations like Everest compared to sea level. Consequently, a pendulum clock would run slower at Mount Everest than it does in Karachi.