Calculate the Kovats retention index for an unknown using the retention times 1.4 min1.4 min for CH4,CH4, 12.2 min12.2 min for octane, 15.9 min15.9 min for the unknown, and 17.5 min17.5 min for nonane.

You would do 1500/4 and the answer is 375

☆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