Why is the sky orange and red at sunrise and sunset

Due to the red light waves being scattered the least by the molecules in the atmosphere, so when the light travels to our eyes we see mostly red/orange/yellow.

Hope this helps! :)

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.