The mass per unit volume of a substance is called density.... - Science

Which of the following are matter?
Chair, air, love, smell, hate, almonds, thought, cold, lemon water, smell of perfume.

Give reasons for the following observation:
The smell of hot sizzling food reaches you several metres away, but to get the smell from cold food you have to go close.

(a) Tabulate the differences in the characteristics of states of matter.
(b) Comment upon the following: rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and density.

Give reasons
(a) A gas fills completely the vessel in which it is kept.
(b) A gas exerts pressure on the walls of the container.
(c) A wooden table should be called a solid.
(d) We can easily move our hand in air but to do the same through a solid block of wood we need a karate expert.

Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Find out why.

Convert the following temperature to celsius scale:
a. 300 K   b. 573 K

What is the physical state of water at:
a. 250°C  b. 100°C ?

For any substance, why does the temperature remain constant during the change of state?