A measure of the average kinetic energy of all the particles in a system. The Kelvin scale is based on Absolute Zero being assigned a value of Zero Kelvin. Absolute Zero is the coldest of all possible temperature values. All other temperature values will be positive in the Kelvin system. It is the primary temperature system used when doing scientific calculations that involve temperature variables.
Weight is the measure of the Earth's gravitational attraction for matter.
If an object were moved to different locations in the Universe, then it would change its weight. This is due to the change in the gravitational field. Consequently, Weight is not constant and would, therefore, be a poor way of measuring the quantity of matter in a given sample. Mass is more reliable because of its constant nature.