computation of SGST & CGST for composit dealer

Can you help me in the following computation
Suppose I am a Composite dealer under GST
I am an manufacturer
My Aggregate turnover was 40,00,000

Computation 1
CGST 40,00,000*1%=40,000
SGST 40,00,000*1%=40,000
Total Tax(2%)=80,000

Computation 2
40,00,000*1%=40,000
Total Tax =40,000
SGST(50%)=20,000
CGST(50%)=20,000

Above two options which one is right . If both are wrong. Then please suggest the right computation
With respect to composition scheme under GST