If i have to leave hangzhou and reach shanghai pudong airport by 11am, is it possible? by which way?

It is possible.
From HZ Railway Station, you can take the early bullet trains such as around the 07:00 to SH Hongqiao Railway Station. Then you can walk to the Hongqiao Airport in about 5 to 10 minutes to take the airport shuttle bus line 1 to Pudong airport in about one and half hours to two hours.