Which one of the following has exactly 3 significant figures

Which of these describe conduction transfer of heat between two objects that are touching transfer of heat by the actual movement of war matter the process in which energy is imitated by one of the object transmitted through space and absorbed by another a process in which energy is released by the molecules breaking apart

Work out sian speed for the first 30 minutes of her journey. give your answer in km/h.

Oxygen and hydrogen gas are at the same temperature t.what is the ratio of kinetic energies of oxygen molecule and hydrogen molecule if oxygen is 16 times heavier than hydrogen.