Time period of a simple pendulum is measured at karachi. what change will occur in the time period, if it is measured on mount everest, explain?

The period of a pendulum is given by 
since Karachi is near sea level, g is larger than it is on Mt. Everest.  That means the pendulum will have a larger period on Mt. Everest than it would in Karachi.

Where is the diagram? you need to be more specific in your question so we can you