For a first order gas phase reaction:
A(g) → 2B(g) + C(g)
Po be initial pressure of A and Pt the total pressure at time 't'. Integrated rate equation is
(a) 2.303/t log (Po/Po - Pt)
(b) 2.303/t log (2Po/3Po - Pt)
(c) 2.303/t log (Po/2Po - Pt)
(d) 2.303/t log (2Po/2Po - Pt)