#2: B. 6.2g
Reason: Fill out the formula with information given.
350J = 2.1 J/(gxc) x m x 27c
Then divide 350J by 2.1 x 27 = m
m = 6.2 grams
#3: B. Exothermic reaction
Reason: If the energy released is less than energy of reactant then it is exothermic.
#4: D. 1.1 x 10^4
Reason: q = 4.184J/(gxc) x 75.0g x 35c (change in temp.)
This equals = 10983
But remember that sig figs are important! So this ends up being 1.1 x 10^4 to accommodate for the sig figs.
Hope this helps ^_^ !