At the top of a high mountain, the weight of an object is: greater than at sea level less than at sea level the same as that at sea level

The gravity at high elevation is comparatively less than at near sea level. It is because gravity value and elevation are inversely proportional to each other. This means that at higher altitude, gravity is low and at the sea level its the maximum.

The gravity value at the equatorial region is minimum but it is maximum at the poles. It is because of the flattening of the earth at the poles and because of the earth's rotation that initiates a centrifugal force at the equator.

increased stability in the completion of fluorine's outer shell.

what is the question here. i think you messed up.