HELP ME PLEASE!!! WILL MARK BRAINLIEST!!

Answer:
See answers below
Explanation:
-44.3 kj/mole * x moles = - 18.7 kj
solve for x = .422 mole dissolved
Mole weight of NaOH is
Na = 22.989 O = 15.999 H = 1.008 gm/mole
= ~~ 40 gm/mole for NaOH
40 gm / mole * .422 mole = 16.88 gm of NaOH