Which of these is an indication that a chemical reaction has occurred?

a. melting of a substance
b. a change of color in a substance
c. boiling of a substance
d. freezing of a substance

Which of the following best supports the concept that genetic information is passed on to offspring from both of their parents, not just one?

How many moles are contained in 5.6 l of h2 at stp

Liquid ammonia is produced at high temperatures and under great pressure in a tank by passing a mixture of nitrogen gas and hydrogen gas over an iron catalyst. the reaction is represented by the following equation. n2(g) + 3h2(g) → 2nh3(g) changing all but one experimental condition will affect the amount of ammonia produced. that condition is a) increasing the concentration of both reactants b) changing the temperature within the tank c) decreasing the pressure within the tank. d) increasing only the amount of nitrogen present.