[lelouch]

The law of the kinetics of nitric oxide when it reacts with oxygen is-d [NO] / dt = k [NO] ² [O2], and the rate constant is 1,16,10^ -5  L ². Mol ^ -2. s ^ -1 to 339 degrees celsius. A balloon contains NO and O2 at 339 degrees celsius. The initial partial pressures of NO and O2 are respectively 155 mm Hg and 345 mm Hg. What is the rate of decrease of NO partial pressure (in mmHg per second)?
R  = 6,6.10^ -8 mmHg / s

[DevaDevil]

so, you have the pressures, temperature, thus can calculate concentrations (n/V).

Where do you get stuck?

[lelouch]

how to get the answer? I'm not getting out how to find the decay rate of partial pressure of NO.

could do the calculations, so I think I understand the logic of the problem.