The rearrangement of cyclopropane to propene at 500

Question

The rearrangement of cyclopropane to propene at 500 °C

(CH₂)₃ ---> CH₃CH=CH₂

is first order in (CH₂)₃ with a rate constant of 6.70×10^-4 s^-1.

If the initial concentration of (CH₂)₃ is 0.196 M, the concentration of (CH₂)₃ will be ______ M after 2592 shave passed

The gas phase decomposition of phosphine at 120 °C

PH₃(g)--->1/4 P₄(g) + 3/2 H₂(g)

is first order in PH₃ with a rate constant of 1.80×10^-2 s^-1.

If the initial concentration of PH₃ is 9.58×10^-2 M, the concentration of PH₃ will be 2.83×10^-2 M after_________ s have passed.