In the normal phase separation column, a solute was found to have retention time of 29.1 min, and an unretained sample had a retention time of 1.05 min when the mobile phase was 50% by volume chloroform and 50% n-hexane. Calculate: a) k for the solute b) a solvent composition that would bring k down to a value of about 10 (hint: use equation 28-3)