Query about cst rate of 1%

Hello friends, please help to guide me through the following doubt: i saw some bills of purchase of certain kind of chemicals from Himachal pradesh on which CST rate of 1% was levied. MY QUERY IS THAT: 1.Why the rate is not 2%? 2.what could be the reasons behind the rate of 1% CST. 3.Is it in the hands of any state to lower the CST rate on the goods sold from its territory or is it due to the rule of LOWER OF LOCAL VAT OR CST that the CST rate here is 1%? Please help.