The rate of decomposition of PH₃ was studied at 961.00 °C. The rate constant was found to be 0.0525 s-¹.

4PH₃ → P₄+ 6H₂

If the reaction is begun with an initial PH₃ concentration of 0.95 M, what will be the concentration of PH₃ after 40.00 s?