A sample of plutonium-239 decays from 341.92 kilograms to 42.74 kilograms. This is 1/8 the original sample. How many half-lives have passed?

Compare and contrast physical changes with chemical changes.

The reactions shown here can be combined to make the overall reaction c(s) + h2o(g) ⇌ co(g) + h2(g) by reversing some and/or dividing all the coefficients by a number. a. c(s) + o2(g) → co2(g) k=1.363×10^69 b. 2 h2(g) + o2(g) → 2 h2o(g) k=1.389×10^80 c. 2co(g) + o2 (g) → 2 co2(g) k=1.477×10^90

Which of these expressions are correct variations of the combined gas law? p1v1t2 = p2v2t1 both