What defines endothermic reactions and exothermic reactions? Select all that apply.
A) Endothermic reactions are chemical reactions that absorb energy from the surrounding environment.
B) Exothermic reactions are chemical reactions that release energy into the surrounding environment.
C) Exothermic reactions are chemical reactions that absorb energy from the surrounding environment.
D) Endothermic reactions are chemical reactions that release energy into the surrounding environment.

In a laboratory determination of the atomic weight of tin, a sample of tin is weighed in a crucible. nitric acid is added, and the reaction proceeds to give a hydrated tin(iv)oxide plus no2and h2o. the hydrated tin(iv)oxide is then heated strongly and reacts as follows: sno2.xh2o(s)sno2(s)+ xh2o(g)the sno2is finally cooled and weighed in the crucible. explain the effect on the calculated atomic weight of tin that would result from each of the following experimental errors: (a)considerable spattering occurs when the nitric acid is added to the tin.(b)the hydrated tin(iv)oxide is not heated sufficiently to change it completely to tin oxide.