When an electron falls from an excited state to ground state, is energy released or absorbed?

Iknow #2 is d. i just need to know why

In an effort to address concerns about global warming, a power plant in portland,oregon is designed to take all of its exhaust gases from its boilers and recycle the co2 using the solvay process to make sodium hydrogen carbonate. the reaction is shown below. nh3(g) + h2o(l) + co2(g) + nacl(aq) → nahco3(aq) + nh4cl(aq) how many liters each of nh3 and co2 (both at stp) would be consumed to produce 3.00 kg of sodium bicarbonate? the volume of both nh3 and co2 would be

How many protons, electrons, and neutrons are in each of the following isotopes? a. zirconium-90 b. palladium-108 c. bromine-81 d. antimony-123