SSC MTS EXAM

Detailed explanation-1: -All phase changes are accompanied by changes in the energy of a system. Changes from a more-ordered state to a less-ordered state (such as a liquid to a gas) are endothermic. Changes from a less-ordered state to a more-ordered state (such as a liquid to a solid) are always exothermic.

Detailed explanation-2: -A phase change is when matter changes to from one state (solid, liquid, gas, plasma) to another. (see figure 1). These changes occur when sufficient energy is supplied to the system (or a sufficient amount is lost), and also occur when the pressure on the system is changed.

Detailed explanation-3: -Changing an object’s phase of matter is just a matter (ha, ha) of adding energy to atoms or taking it away. Heating adds energy to atoms, and cooling takes energy away from atoms. If you fried an ice cube in a pan on a stove, you would see all three phases of matter – ice cube, liquid water, and water vapor.

Detailed explanation-4: -The energy that is changing during a phase change is potential energy. During a phase change, the heat added (PE increases) or released (PE decreases) will allow the molecules to move apart or come together. Heat absorbed causes the molecules to move farther apart by overcoming the intermolecular forces of attraction.