Heat loss could be reduced by:

• A. Insulation of beaker.
• B. Covering beaker with a lid.
• C. Using a smaller beaker.
• D. Placing the beaker in a draft-free area.

Answer: (A)

The key idea is to slow down how quickly energy leaves the hot liquid. Heat escapes from a beaker mainly by conduction through the walls, convection into the surrounding air, and evaporation from the surface. Insulating the beaker adds a layer with trapped air that has very low thermal conductivity, which reduces heat transfer through the walls and also helps limit convection just outside the beaker. This combination significantly lowers heat loss, so the liquid stays hot for longer.

Covering with a lid helps by reducing evaporation and some surface convection, but it doesn’t cut heat loss through the walls as effectively as insulation. Using a smaller beaker would reduce surface area a bit, but if you’re still heating the same amount of liquid, the overall heat loss isn’t cut as much. Placing the beaker in a draft-free area reduces convective heat loss from surrounding air, but insulation tackles multiple routes of heat transfer at once.