An experiment takes 10 minutes to raise the temperature of water in a container from 0∘C to 100∘C and another 55 minutes to convert it totally into steam by a heater supplying heat at a uniform rate. Neglecting the specific heat of the container and taking specific heat of water to be 1 cal/g∘C , the heat of vapourization according to this experiment will come out to be :
a. 560 cal/g
b. 550 cal/g
c. 540 cal/g
d. 530 cal/g