Science CBSE ix Chapter 6 - Tissues - Answer of question on Page 69 Q1

What is a tissue?

Answer

Tissue is a group of cells that are similar in structure and are organised together to perform a specific task.

Science CBSE ix Chapter 3 - Atoms and Molecules - Answer of question on Page 40 Q1

Question 1:

Calculate the molecular masses of H2, O2, Cl2, CO2, CH4, C2H6, C2H4, NH3, CH3OH.

Answer

Molecular mass of H2 = 2 × Atomic mass of H

= 2 × 1

= 2 u

Molecular mass of O2 = 2 × Atomic mass of O

= 2 × 16

= 32 u

Molecular mass of Cl2 = 2 × Atomic mass of Cl

= 2 × 35.5

= 71 u

Molecular mass of CO2 = Atomic mass of C + 2 × Atomic mass of O

= 12 + 2 × 16

= 44 u

Molecular mass of CH4 = Atomic mass of C + 4 × Atomic mass of H

= 12 + 4 × 1

= 16 u

Science CBSE ix Chapter 3 - Atoms and Molecules - Answer of question on Page 40 Q2

Question 2:

Calculate the formula unit masses of ZnO, Na2O, K2CO3, given atomic masses of Zn = 65 u, Na = 23 u, K = 39 u, C = 12 u, and O = 16 u.

Answer

Formula unit mass of ZnO = Atomic mass of Zn + Atomic mass of O

= 65 + 16

= 81 u

Formula unit mass of Na2O = 2 × Atomic mass of Na + Atomic mass of O

= 2 × 23 + 16

= 62 u

Formula unit mass of K2CO3 = 2 × Atomic mass of K + Atomic mass of C + 3 × Atomic mass of O

= 2 × 39 + 12 + 3 × 16

= 138 u

Science CBSE ix Chapter 3 - Atoms and Molecules - Answer of question on Page 32 Q1

Question 1:

In a reaction, 5.3 g of sodium carbonate reacted with 6 g of ethanoic acid. The products were 2.2 g of carbon dioxide, 0.9 g water and 8.2 g of sodium ethanoate. Show that these observations are in agreement with the law of conservation of mass.

Sodium carbonate + ethanoic acid sodium ethanoate + carbon dioxide + water

Answer

In the given reaction, sodium carbonate reacts with ethanoic acid to produce sodium ethanoate, carbon dioxide, and water.

Mass of sodium carbonate = 5.3 g (Given)

Mass of ethanoic acid = 6 g (Given)

Mass of sodium ethanoate = 8.2 g (Given)

Mass of carbon dioxide = 2.2 g (Given)

Mass of water = 0.9 g (Given)

Now, total mass before the reaction = (5.3 + 6) g

= 11.3 g

And, total mass after the reaction = (8.2 + 2.2 + 0.9) g

= 11.3 g

Total mass before the reaction = Total mass after the reaction

Hence, the given observations are in agreement with the law of conservation of mass.

Science CBSE ix Chapter 2 - Is Matter Around Us Pure - Answer of question on Page 15 Q2

Question 2:

List the points of differences between homogeneous and heterogeneous mixtures.

Answer

A homogeneous mixture is a mixture having a uniform composition throughout the mixture. For example: salt in water, sugar in water, copper sulphate in water

A heterogeneous mixture is a mixture having a non-uniform composition throughout the mixture. For example: sodium chloride and iron fillings, salt and sulphur, oil and water

Science CBSE ix Chapter 2 - Is Matter Around Us Pure - Answer of question on Page 15 Q1

Question 1:

What is meant by a pure substance?

Answer

A pure substance is the one that consists of a single type of particles, i.e., all constituent particles of the substance have the same chemical nature. Pure substances can be classified as elements or compounds

Science CBSE ix Chapter 1 - Matter in Our Surroundings - Answer of question on Page 3 Q4

Question 4:

What are the characteristics of particles of matter?

Answer

The characteristics of particles of matter are:

(i) Particles of matter have spaces between them.

(ii) Particles of matter are continuously moving.

(iii) Particles of mater attract each other.

Science CBSE ix Chapter 1 - Matter in Our Surroundings - Answer of question on Page 3 Q3

Question 3:

A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?

Answer

The ability of a diver to cut through water in a swimming pool shows that matter is made up of particles.

Science CBSE ix Chapter 1 - Matter in Our Surroundings - Answer of question on Page 3 Q1

Question 1.

Which of the following are matter?

Chair, air, love, smell, hate, almonds, thought, cold, cold drink, smell of perfume.

Answer

Anything that occupies space and has mass is called matter. Matter can exist in three physical states—solid, liquid, and gaseous.

Chair and almond are forms of matter in the solid state.

Cold drink is a liquid state of matter.

Air and smell of perfume are gaseous states of matter.

Note: The sense of smell is not matter. However, the smell or odour of a substance is classified as matter. The smell of any substance (say, perfume) is the gaseous form of that substance which our olfactory system can detect (even at very low concentrations). Hence, smell of perfume is matter.

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