29. In which method of transfer of heat do the molecules travel from the hot to the cold portion?
A. Conduction
B. Convection
C. Radiation
D. All of the choices.

30. The inside of a solar cooker and the pipes of a solar water heater are printed black because black surface is a
A. Good reflection of heat.
B. Poor absorber of heat.
C. Good absorber of heat,
D. Good radiator of heat.
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