Which of these is the best evidence that a chemical reaction occurs when coal burn

Which statement best describes the relationship between period and frequency of light waves? a) in wave b the period increases and the frequency decreases from wave a. b) in wave a the period increases and the frequency decreases from wave b. c) in wave b the period is shorter and the frequency is greater than in wave a. d) in wave a the period is shorter and the frequency is greater than in wave b.

In france, grapes are 1.95 euros per kilogram. what is the cost of grapes, in dollars per pound, if the exchange rate is 1.14 dollars/euro? (2.6)

What’s the theoretical yield of solid lead