Which phrase describes a scientific theory?

Word equation for k(s) +h2o(l) yield koh (aq) + h2

Sum of brother and sisters age is 26. four times the brothers age is subtracted from three times the sisters age, the difference is 8. what are the ages of the brother and sister?

The reaction below shows a system in equilibrium. how would a decrease in temperature affect this reaction? a. the rate of formation of the gases would increase. b. the equilibrium of the reaction would shift to the left. c. the equilibrium would shift to cause the gases to sublime into solids. d. the chemicals on the left would quickly form the chemical on the right.