Is Matter Around Us Pure — Science STD 9 — Question

Why does the temperature remain constant during the boiling of water even though heat is supplied continuously?

Explain why, we can easily move our hand in air but to do the same through a plank of wood, we need a karate expert.

Bromine and air take about 15 minutes to diffuse completely but bromine diffuses into a vacuum very rapidly. Why is this so?

When a gas jar containing air is inverted over a gas jar containing bromine vapour, the red-brown bromine vapour diffuse into air. Explain how bromine vapour diffuse into air.

Write a method to separate a mixture of sand and potash alum.

Complete the following table.

Elements	Atomic number	Mass number	Protons	Electrons	neutrons	Electronic configuration	Valency
Chlorine	17	___	___	___	18	___	___
Silicon	___	28	___	14	___	___	___
Fluorine	___	___	9	___	10	___	___

Give an example in which physical and chemical changes take place together.

How are given mass, molar mass and number of moles related to each other?

How will you separate water from mustard oil?