Dear Mr. Chang, I am worried about your proposal to install a groundwater heating system in my daughter’s school.
I don’t think that water at a temperature of 30°C has enough energy to heat the school. If the school is too cold, the students won’t be able to focus on learning.

Respond to David Li’s letter. Explain how the groundwater system could heat the air in the school. Explain what would happen to the air temperature at Riverdale School if the groundwater system were used. Use the terms stability and change in your explanation.

The two naturally occurring isotopes of chlorine are 35cl (34.969 amu, 75.77%) and 37cl (36.966 amu, 24.23%). the two naturally occurring isotopes of bromine are 79br (78.918 rm amu, 50.69%) and 81br (80.916 amu, 49.31%). chlorine and bromine combine to form bromine monochloride, brcl. 1. how many peaks will be present in a mass spectrum for brcl? the four combinations of molecule possible given these four isotopes are: 81br37cl, 81br35cl, 79br37cl, and 79br35cl. 2. what are the masses of the four different brcl molecules? express the masses using six significant figures, in decreasing numeric order (highest to lowest), separated by commas.