Q1: A cube, sphere & a thin circular plate (all having same mass and made of same material) are all heated to 300°C and allowed to cool in natural air. Which one will cool the slowest ?

ANS:C - Sphere

Among the given options, the sphere will cool the slowest. This is because the sphere has the smallest surface area-to-volume ratio compared to the cube and the thin circular plate. The rate of heat loss through convection and radiation to the surrounding air depends on the surface area of the object. Objects with smaller surface area-to-volume ratios have less surface area available for heat transfer per unit volume, leading to slower cooling rates. The sphere has the smallest surface area-to-volume ratio among the three shapes, followed by the cube, and then the thin circular plate. Therefore, the sphere will lose heat at a slower rate compared to the cube and the thin circular plate when they are all initially heated to the same temperature and allowed to cool in natural air.