Coal is a combustible solid, petrol is a combustible liquid and CNG is a combustible gas

Materials which are lighter 'than water, float on water: Wood and oil are lighter than water and float on it.

The materials through which objects are partially visible, are known as translucent materials, e.g., butter paper

Butter paper and oiled paper are two examples of translucent objects

Steel is a good conductor of heat, so it cannot be used as handle in utensils

Water is called universal solvent as it can dissolve maximum materials.

Metals when exposed to air react with moisture and gases present in it, thereby forming a dull layer of some other compounds on it.

We need to group materials for our convenience. Grouping helps us to locate things easily.

Polythene and glass container are the transparent objects through which things can be seen clearly.

Blackboard and wooden doors are objects which are made from opaque materials.

Cotton ball initially floats on water but after few minutes (i.e. 10 min), it sinks because it absorbs water.

Due to transparent nature of glass or plastic container, biscuits, sweets, etc., can be seen easily by buyers, so shopkeepers do like this.

Wood and plastic are the materials which are float on water.

Bowls and mirrors are made from glass.

Plastic and wood do not conduct electricity.