The heat required to vaporize 650 grams of liquid with a heat of vaporization of 723 joules/grams is 470,000 J ( answer E)
calculation
Heat (Q) = m Hv where,
m(mass)= 650 g
HV( heat of vaporization) = 723 J/g
heat is therefore = 650 g x 723 J/g =469950 J
round off 469950 j into nearest 10,000 = 470,000 J ( answer E)