A vacuum-insulated flask contains 400 g of liquid nitrogen at its boiling point. A 50 W electrical immersion heater is placed into the liquid to vaporise a portion of it.
Calculate the time taken for the mass of liquid nitrogen remaining in the flask to decrease to 250 g.
(Specific latent heat of vaporisation of nitrogen = 2.0 × 105 J/kg)
10 s10\text{ s}10 s
600 s600\text{ s}600 s
1000 s1000\text{ s}1000 s
1600 s1600\text{ s}1600 s
27 exam-style questions on OCR GCSE Physics Changes of state. Each one has a worked solution and a mark scheme showing where the marks go.