Is 6-7 hours enough to explore best tourist places of Kochi?

Hi guys, I need some help in planning my Kerala trip. I will reach Kochi at 11pm. I am planning to leave to Munnar next day at around 1pm. So I am planning to visit places in Kochi from 7 am till 1 pm. Is this a sufficient time to visit all the best places in Kochi? Please help. I can also extend my stay to 1 full day in Kochi but I think it's not required.