RBSE Solutions for Class 6 Science Chapter 5 Let Us Know the Substance

RBSE Solutions for Class 6 Science Chapter 5 Let Us Know the Substance are part of RBSE Solutions for Class 6 Science. Here we have given Rajasthan Board RBSE Class 6 Science Chapter 5 Let Us Know the Substance.

Board	RBSE
Textbook	SIERT, Rajasthan
Class	Class 6
Subject	Science
Chapter	Chapter 5
Chapter Name	Let Us Know the Substance
Number of Questions Solved	56
Category	RBSE Solutions

Rajasthan Board RBSE Class 6 Science Chapter 5 Let Us Know the Substance

Intext Questions

Question 1.
What is substance? (Page 37)
Answer:
Things around us which have weight and occupy space are called substance.

Question 2.
Are all substances similar? (Page 37)
Answer:
No, all substances are not similar.

Question 3.
How many types of substances are there, how they are classified? (Page 37)
Answer:
On the basis of physical composition, substances are of four types. On the basis of chemical composition, substances are of three types.

Question 4.
You all have seen stone, wood, things made-up from plastic and iron like chair, wooden block etc. around your school and homes. What are the shape and volume of these substances? (Page 38)
Answer:
These things have definite shape and definite volumes.

Question 5.
What happens on compressing them?(Page 38)
Answer:
They do not get compressed.

Question 6.
What is a substance made up of? (Page 41)
Answer:
A substance is made up of small particles.

Question 7.
Have you ever thought what this small particle is? What is this known as? What is its structure? (Page 41)
Answer:
The undivided particle of substance is known as atom. We cannot see those atoms through naked eyes. Atom is made up of three particles proton, electron and neutron.

Question 8.
What are element, compound and mixture? (Page 43)
Answer:
Element – The substances made up of only one type of atom are called elements.
Compound – When two or more atoms combine through chemical reaction in a fixed ratio, a compound is formed.
Mixture – It is formed when two or more compounds or elements are mixed in a ratio.

Question 9.
All have seen utensils of brass and steel, air, glass, H₂O, stone, etc. Are these all made up of one type of substances? (Page 44)
Answer:
No, all these substances are formed when two or more compounds or elements are mixed in a ratio.

Activities

Activity – 1

Question 1.
Collect few things from your nearby places and write their properties in Table 5.1
Answer:
Table 5.1 Things and their properties

S.No.	Things	Weight	Area occupied
1.	Stone	Have weight	occupy space
2.	Water	Have weight	occupy space
3.	Sugar	Have weight	occupy space
4.	Plastic bucket	Have weight	occupy space
5.	Naphthalene	Have weight	occupy space

Activity-2 (Page 37)

Question 1.
What can be stated from this experiment.
Answer:
From this experiment, we can say that substances have three states of matter-solid, liquid and gas.

Activity – 3 (Page 38)

Question 1.
What do you conclude from the above experiment?
Answer:

1. We conclude that wooden block and iron rod do not get compressed.
2. Solids have a definite shape and a definite volume.
3. The particles in solids are very close to each other.

Activity – 4 (Page 39)

Question 1.
What do you conclude from this experiment?
Answer:
We conclude that

1. Liquids have definite volume but the shape of liquid is dependent on the container in which it is poured.
2. The particles of liquid are little far from each other.
3. Liquid can flow and can be poured from one container to another.

Activity – 5 (Page 40)

Question 1.
Are butter and jelly solid or liquid? What happens when we spread butter on bread?
Answer:
Butter does not change to liquid but when we heat it, it changes to liquid. Jelly is in liquid state, but when we refrigerate it, it changes to solid. These types of substances have properties of both solid and liquid. They do not flow when we keep them on room- temperature.

Activity – 6 (Page 40)

Question 1.
What do you observe?
Answer:
We see that air takes the shape of balloon. Now open the thread slowly, on opening the balloon air comes out and disappear in atmosphere.

Exercises

Choose the correct option

Question 1.
The gaseous state has
(a) fixed shape
(b) unfixed shape and volume
(c) fixed volume
(d) fixed mass
Answer:
(b) unfixed shape and volume

Question 2.
The main particle of outer part of an atom is
(a) proton
(b) neutron
(c) proton and neutron
(d) electron
Answer:
(d) electron

Question 3.
The substance made up of only one type of particle is
(a) compound
(b) element
(c) mixture
(d) mixed metal
Answer:
(b) element

Question 4.
Sugar, salt, glass, plastic are called
(a) Element
(b) Compound
(c) Mixture
(d) All of the above
Answer:
(b) Compound

Fill in the blanks

1. …………… and ……………… are present in the nucleus of atom.
2. The particles of solid are …………….. to each other. while particles of gases are
3. Sugar is a compound while its syrup is a ……………..
Answer:
1. Proton, neutron
2. very close, at large distances
3. mixture

Match the following correctly

Column 1	Column 2
1. Iron	A. Atom
2. Salt	B.  Mixture
3. Sharbet	C. Element
4. Electron, proton and neutron	D. Compound

Answer:
1. (c)
2. (d)
3. (b)
4. (a)

Short Answer Type Questions

Question 1.
Write names of 5 compounds used in our daily life.
Answer:
Five compounds used in our daily life are

1. Common salt
2. Water
3. Soap
4. Baking soda
5. Sugar

Question 2.
Draw a labelled diagram of structure of atom.
Answer:

Question 3.
Identify elements, compounds and mixture from the following:
oxygen gas, iron, sugar, salt, hydrogen gas, sand, brass, soap, surf, sugar-syrup, sharbet, air.
Answer:
Element – Oxygen gas, iron, hydrogen gas, brass.
Compound – Sugar, salt, soap, surf.
Mixture – Syrup, sharbet, air.

Long Answer Type Questions

Question 1.
Explain with experiments the state of matter.
Answer:
There are three states of matter solid, liquid and gas.
Experiment 1: Press a wooden block and put it on a table. The wooden block does not get compressed and has unchanged shape and size.
Result: Solids have a definite shape and a definite volume. The particles in solid are very close to each other.

Experiment 2 : Pour water from a bottle to a glass. It takes the shape of glass.
Result: Liquids have fixed volume but the shape of liquid depends on the container in which it is poured. The particles of liquid are little far from each other.

Experiment 3 : Inflate a balloon and tie it with a thread. Then, open the thread and let it free.
Result: Gases do not have definite shape and volume and their particles diffuse at a large distances.

Question 2.
Define element, compound and mixture with examples.
Answer:
Element: The atoms of an element are similar in their properties. For examples iron, copper, aluminium, gold etc.
Compound: When two or more atoms combine through a chemical reaction in a fixed ratio, a compound is formed. For example, sugar, glass, salt, soap, etc.
Mixture: Mixture is a substance which is formed when two or more compounds or elements are mixed in any ratio. For example, sharbet, air, sand, etc.

Question 3.
Differentiate between atom and molecule with example.
Answer:

Atom	Molecule
1. It is the fundamental unit of substance.	1. Molecules are formed from two or more than two atoms.
2. It does not exist independently. Eg. Gold, aluminium, silver	2. Molecules exist independently. Eg. H2, O2, H2O, CO2, etc.

Question 4.
Explain the making of water molecule with diagram.
Answer:
Molecules of oxygen and hydrogen are formed from two hydrogen atoms and two oxygen atoms respectively but a molecule of water (11,0) is formed from two atoms of hydrogen and one atom of oxygen.

Practical Work

Question 1.
Make the model of structure of atom on a cardboard with the help of balls or marbles.
Answer:

Question 2.
Draw a chart of symbols of elements and hang in your class.
Answer:
Chart of symbols of elements

Name of Element	Symbol	Name of Element	Symbol
Hydrogen	H	Bromine	Br
Carbon	C	Calcium	Ca
Fluorine	F	Chlorine	a
Nitrogen	N	Magnesium	Mg
Phosphorus	P	Sodium	Na
Sulphur	S	Copper	Cu
Oxygen	o	Iron	Fe
Potassium	K	Silver	Ag
Gold	Au	Mercury	Hg
Aluminum	Al	Cobalt	Co

Other Important Questions

Multiple Choice Questions

Question 1.
Which of the following is not a substance?
(a) Water
(b) Smoke
(c) Vision
(d) Dust
Answer:
(c) Vision

Question 2.
the states of water are:
(a) Two
(b) Three
(c) Four
(d) Five
Answer:
(b) Three

Question 3.
Which of the following state of matter has definite shape and volume ?
(a) Solid
(b) Liquid
(c) Gas
(d) Plasma
Answer:
(a) Solid

Question 4.
Which of the following is present in the nucleus of atom ?
(a) Proton
(b) Electron
(c) Neutron
(d) Proton and neutron
Answer:
(d) Proton and neutron

Question 5.
The formula of common salt is
(a) MgCl₂
(b) NaCl
(c) HCl
(d) CO₂
Answer:
(b) NaCl

Fill in the blanks

1. The different forms of a substance are called …………… of matter.
2. …………. can flow and can be poured from one container to another.
3. Air is a ………… of gases.
4. All the substances are formed by small ………………
Answer:
1. states
2. Liquids
3. mixture
4. particles

Very Short Answer type Questions

Question 1.
What is a substance?
Answer:
A substance is a thing which has weight and occupy space.

Question 2.
What are the states of matter or substance on the basis of physical composition?
Answer:
Three states – solid, liquid and gas.

Question 3.
Butter is considered in both states solid and liquid, why?
Answer:
Because butter is solid at room temperature but it changes to liquid state on heating.

Question 4.
How many atoms are there in a molecule of water?
Answer:
There are three atoms. One of oxygen and two of hydrogen.

Question 5.
What is the central part of an atom called?
Answer:
The central part of an atom is called nucleus.

Question 6.
How many elements have been discovered till now.
Answer:
118 elements

Question 7.
Classify element and mixture from the following :
Copper, brass, hydrogen, sand.
Answer:

1. Element – copper, hydrogen.
2. Mixture – brass, sand.

Question 8.
Why is air called a mixture?
Answer:
Air is a mixture because it has many gases in indefinite ratio.

Short Answer type Questions

Question 1.
Classify the substances.
Answer:
Classification of substances 

Question 2.
The volume of liquid is definite but not the shape and size. Explain it with the help of two examples.
Answer:
Liquids have definite volume but the shape of liquid is dependent on the container in which it is poured :

1. When we pour water from bottle to a glass, the water takes the shape of that glass.
2. When we pour water back from glass to bottle, the volume remains the same.

Question 3.
Butter and jelly both have the properties of solids and liquid explain.
Answer:
When butter is kept at room temperature, then it is in solid state but on heating it changes into liquid state. Similarly, when jelly is prepared, it is in liquid state, but when it is freezed, it turns into solid. Thus, they have the properties of both solids and liquid.

Question 4.
How will you explain that the shape and volume of gas are not definite?
Answer:
The smoke of incense stick diffuses everywhere when it is lighted. We can feel the smell of smoke from vehicles, smell of waste etc. Thus, clearly we can say that the shape and volume of gas are not definite.

Question 5.
Draw a diagram showing the changes of states of matter.
Answer:

Question 6.
What do you understand by plasma?
Answer:
Plasma is a saturated gaseous state. This state is found in sun, stars, tube-lights and picture tubes of T.V

Question 7.
Explain the formation of hydrogen molecule with diagram.
Answer:
Two atoms of hydrogen form a molecule of hydrogen.

Long Answer type Questions

Question 1.
Why is Maharshi Kanad famous? How did he get this name?
Answer:
In vedic period, the great philosopher Kanad authored Veseshik Sutra which is basic nuclear physics for Scientists of West. He propounded the atomic theory of Veseshik philosophy. He gave the concept that atom combines together to make molecules. He ateTandual particles (Sama rice in Hindi) during his meditation that made his name ‘Kanad’. He was the originator of the particle-molecule theory and hence called as Kanad.

Question 2.
Explain briefly the structure of atom.
Answer:
Greek philosopher Demokrits name the undivided particle of substance as atom. An atom is made up of three particles:

1. Proton (p)
2. Electron (e)
3. Neutron (n)

An atom has two structural parts-
1. Nucleus (inner part)
2. Electric shell (outer part)

The inner part of atom is called Nucleus. It has two particles:
1. Proton (p) – It is positively changed.
2. Neutron (n) – It is electrically neutral.
The outer part of atom consist of negatively charged particles called electron (e). They, circulate around nucleus in definite orbits.

Question 3.
Write the names of five compounds along with their chemical formulae.
Answer:
Five Compounds and their Formula.

S.No.	Name of compound	Formula
1.	Water	H2O
2.	Sodium chloride	NaCl
3.	Carbon dioxide	CO2
4.	Magnesium chloride	MgCl2
5.	Hydrochloric acid	HCl

Question 4.
Give brief description of Satyendra Nath Bose and his work.
Answer:
Sateyandra Nath Bose was born on 1st January, 1894. He was known as the father of statistical engineering. Research of S.N. Bose and Anarico Fermi made possible to differentiate particles of physics into two parts Boson and Fermions. National Science Council awarded S.N. Bose with Meghnad Saha Smarak gold medal, in 1954, he was awarded with Padma Vibhushan.

The principle propounded by Bose was published by the eminent scientist Einstein. This principle is named as Bose Einstein statistics. With the help of Einstein, S.N. Bose discovered fifth state of matter as Bose Einstein Condensation which is scientifically proved. That is why, he is also called Indian Einstein.

We hope the RBSE Solutions for Class 6 Science Chapter 5 Let Us Know the Substance will help you. If you have any query regarding Rajasthan Board RBSE Class 6 Science Chapter 5 Let Us Know the Substance, drop a comment below and we will get back to you at the earliest.