Question

I have the answers for these but can you please explain to me how to get them? Thanks.

Place the following in order of decreasing lattice energy.
KBr RbI MgS
a. KBr > RbI > MgS
b. KBr > MgS > RbI
c. RbI > KBr > MgS
d. MgS > KBr > RbI
e. MgS > RbI > KBr

I am confused about lattice energy or even how to figure it out?

Which of the following species are paramagnetic?
a. Ca
b. S2-
c. Zn2+
d. Sr2+
e. None of the above are paramagnetic.
Are paramagnetic the ones that have unpaired electrons???

According to valence bond theory, the sigma bond between C and H in C2HCl is formed from the overlap of which two orbitals?

Carbon Hydrogen
a. sp s

Answer 1

Here is a site that give you some insight on lattice energy.
http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch7/lattice.html

Yes, paramegnetic species will be those that have unpaired electrons.

s and p.