Class 9 - Chemistry: Matter In Our Surroundings

Which of the following is NOT matter

• Smell of perfume

• Energy

• Air

• chair

Answer explanation

All the others have mass and occupy space and can be perceived by our senses

Which one of these are part of the classification of matter made by the early Indian philosophers

• Bose Einstein condensates

• Salt

• Sugar

• Sky

Answer explanation

The Early Indian philosophers classified matter into 5 forms:

1. 1. Vayu or Air

2. 2. Jal or Water

3. 3. Prithvi or Earth

4. 4. Akash or sky

5. 5. Agni or fire

Which is NOT a characteristic of matter

• Matter is made of small particles called atoms

• Particles of matter are continuously moving

• Particles of matter have intermolecular force of attraction and space

• Matter has volume and definite density

The reason for the activity 1.2 where on repeated dilution the colour of KMnO4 solution though becoming slight did not completely fade is:

• The particles of matter are continuously moving

• The particles of matter are having enough space

• The particles of matter have intermolecular force of attraction

• The particles of matter are very small and they further divide into smaller particles

Answer explanation

Particles of matter are made of very tiny particles (bigger than atoms) called molecules which are connected due to intramolecular force of attraction and when they are dissolved these molecules separate from each other into small molecules

The change of state of matter from Vapour / Gaseous directly into Solid state

• Sublimation
• Condensation
• Bose Einstein Condensation
• Deposition

20g of ice at 258K is added to 50g of water at 373K find the final temperature of the system after thermal equilibrium. (Assume there is no heat exchange with the atmosphere)

• 65*C

• 55*C

• 305K

• 361K

Answer explanation

mass of ice(mi) = 20g

mass of H2O(mw) = 50g

temperature 1 = 258K

temperature 2 = 373K

Final temperature = Tf

Energy gained by ice = Energy lost by H2O

Q1 = Q2

mc(dt) + mlf = mc(dt2)

20*0.5*(273-258) + 20*80 = 50*1*(373 - Tf)

10*15 + 1600 = 50*100 - 50*Tf (measured in *C)

1750 = 5000 - 50Tf

Tf = (5000 - 1750)/50

Tf = 65*C

Rate of diffusion is:

• Inversely proportional to mass
• Directly proportional to density
• Inversely proportional to square root of mass
• Directly proportional to square root of density

Convert 30*F to Kelvin

• 275K

• 222K

• 272K

• 235K

Answer explanation

Temperature in Farenheit = 30*F

Celsius = (Farenheit-32)*(5/9)

C = (30-32)*(5/9)

C = -10/9

K = 273 + C

K = 273 + (-10/9)

K = 271.88888...

K = 272(approx)

T = 272K

Crystalline solids are not:

• having definite geometry
• Isotropic
• having sharp melting point
• classified into 7 types

Assertion: Boyle's law does not work when air is blown into a balloon were pressure and volume of the balloon increases. Reasoning: Boyle's law is not applicable for closed containers

• If both assertion and reasoning is true and the reason is the correct explanation of the statement

• If both assertion and reasoning are true and the reason is not the correct explanation of the statement

• If assertion is true and reason is false

• If assertion is false and reason is true

Answer explanation

Boyle's law is only applicable when temperature and number of molecules are constant. When we blow air into the balloon the number of molecules does not remain same hence boyle's law does not work in this case.