If the distance between the foci of an ellipse is $6$ and the length of the minor axis is $8$,then the eccentricity is

Which of the following alkaline earth metals is the strongest reducing agent?

Which of the following is the correct increasing order of ionic character?

The magnetic needle of a vibration magnetometer makes $12$ oscillations per minute in the horizontal component of the earth's magnetic field. When an external short bar magnet is placed at some distance along the axis of the needle in the same line,it makes $15$ oscillations per minute. If the poles of the bar magnet are interchanged,the number of oscillations it makes per minute is

Which of the following is the strongest Lewis acid?