Matter and Its Composition

Solids have a definite shape while liquids do not

Solids have both a definite shape and a definite volume because their particles are tightly packed with strong intermolecular forces. Liquids have a definite volume but NO definite shape – they take the shape of their container. Option B is wrong because it is gases (not solids) that have no definite volume. Option C is wrong because it is the reverse – liquids flow but solids generally do not. Option D is wrong because solids typically have HIGHER density than liquids.

Kinetic energy

Kinetic energy is the energy an object has due to its motion. Particles of matter are always in random motion and possess kinetic energy. This energy increases with increase in temperature, which is why particles move faster when heated. Option B (Potential energy) is stored energy due to position, not motion. Option C (Chemical energy) is energy stored in chemical bonds. Option D (Thermal energy) is related to heat, which is a result of kinetic energy but is not the specific term used here.

Applying high pressure to the gas

The state of a substance can be changed by applying pressure. Gases, when subjected to high pressure, get compressed – their molecules are pushed closer together, intermolecular forces increase, and the gas converts to liquid. LPG stands for Liquefied Petroleum Gas. When the regulator valve is opened, pressure is released and LPG comes out as gas for burning. Option B is wrong – cooling reduces temperature, and 'cooling to high temperature' is contradictory. Option C is wrong – water is not added to LPG cylinders. Option D is wrong – the size of molecules does not change; it is the SPACE betwe

Air has mass

The metre scale tilts towards the inflated balloon because the inflated balloon contains air, which has mass. The deflated balloon lost its air, so it became lighter. The heavier side (with more mass) tilts down. This experiment specifically proves that air has mass – a key property of matter. Option B is wrong because this experiment proves air DOES have mass. Option C is wrong because the experiment compares two identical balloons – one with air and one without. Option D is wrong because the experiment uses equally inflated balloons before puncturing.