In the celebrated equation e = mc2, the c2 is the

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In the celebrated equation e = mc2, the c2 is the proportionality constant of energy and mass.

This famous equation was proposed by Albert Einstein in 1905, and implies that when there is a certain mass, there is a certain amount of Energy associated with it even is the mass is in a steady state. The proportionality constant c² is the speed of light squared. 

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☆ionisation energy increases across a period from na -> ar☆ionisation energy decreases down a group from li -> fr☆ionic radius decreases across a period from na -> cl☆ionic radius increases down a groupfrom f -> ii hope it clarifies your doubts

The answer is bhope this