Solution:
Chlorophyll b is present in Chlorophyceae but not in Phaeophyceae and Rhodophyceae. Chlorophyll a is present in all algae. zoospores and isogamy are present in phaeophyceae and chlorophyceae.
Feature seen in Chlorophyceae but not in Rhodophyceae and Phaeophyceae is
Chlorophyll b is present in Chlorophyceae but not in Phaeophyceae and Rhodophyceae. Chlorophyll a is present in all algae. zoospores and isogamy are present in phaeophyceae and chlorophyceae.