How long will it take a 50w heater to melt 100g of ice at 0°c?

50 W = 50 J / s

Heat required to melt an object is given by the equation

Q = mL, Q is heat required, m is mass to be melted and L is latent heat of fusion

Given mass to be melted m =.1 kg

L = latent heat of fusion of ice = 334000 J / kg

Q =.1 x 334000

= 33400 J

power of heater = 50 J / s

or it gives heat 50 J / s

time required = 33400 / 50

= 668 s

= 11.33 minutes.