During an experiment water was heated in a container covered with a glass lid. the following observations were recorded.
observation 1: water droplets form on the inside of the glass lid.
observation 2: bubbles rise as the water starts boiling.
based on the observation, justify the type of change (physical or chemical) that took place.

Explanation:

Physical change: Generally, there is a change in state, shape or size with no formation of any new substance. These changes are reversible in nature.

Chemical change: Generally, there is a formation of any new substance. These changes are irreversible in nature.

Observation 1 : Water droplets form on the inside of the glass lid.

This means that water vapors produced from the heating of the water are get converted into liquid state that is into water.

This process of the conversion of gaseous phase into liquid phase is known as Condensation.

Since, only state of the substance is changing which means that it is a physical change.

Observation 2 : Bubbles rise as the water starts boiling.

This is is because when water starts boiling , molecules of water started getting converted into gaseous state that is into water vapors.

This process of the conversion of liquid phase into gaseous phase is known as Evaporation.

Here also only state of the substance is changing which means that it is also a physical change.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.