Gurgaon
2012-13
Name:
Class: IX
Subject: Science (Physics)
Worksheet 1
Task 1:
Task 2:
Date: 04 July 2012
Topic: Motion
Assessment paramters:
Task1:
Task 2:
Resource: www.cbse.nic.in (teacher’s manual)
Questions are to be solved in Physics Note book and submitted on following dates
Submission Dates:
IX A: Day 5 (Wed—11th July)
IX B: Day 4 (Tuesday --10th July)
IX C: Day 6 (Thursday, 12th July)
IX D: Day 6 (Thursday, 12th July)
Gurgaon
2012-13
Chemistry
Name:
Class: IX
Date: 05 July 2012
Subject: Science ( Chemistry)
us pure
Worksheet 1
Topic: Is matter around
Learning Material
MATTER
MIXTURES
PURE SUBSTANCES
More than one
substance present
Only one substance
present: no
impurities
ELEMENTS
COMPOUNDS
HOMOGENEOUS
MIXTURES
HETEROGENEOUS
MIXTURES
Cannot be divided
into simpler
substances
Made from
elements
chemically
bonded together
(SOLUTIONS)
(SUSPENSIONS AND
COLLOID)
Substances completely
mixed.Mixtures exits in
one state/phase
Substances
seperae.One state
spread throughout
the other
What is a pure substance?
A pure substance means that it is a single substance.A pure substance consists of a single type
of particles. A pure substance represents a single substance.
How to test for a pure substance?
The purity of a substance can be tested by checking its melting point and boiling point.A pure
substance has a fixed melting point or boiling point at constant pressure.
The melting and boiling point of a substance will change if it contains even a tiny amount of
another substance.
What are the types of Pure Substances
On the basis of their chemical composition, the substance can be classified as
(i) Elements
(ii) Compounds
Robert Boyle was the first scientist to use the term element in 1661. Antoine Laurent Lavoisier,
a French chemist was the first to establish an experimentally useful definition of an
element.According to him an element may be defined as:“A substance which can neither be
broken down into simpler substances nor formed from two of more simple substances by any
known physical or chemical process”.
The elements are regarded as the building blocks of the universe.Among all the known
elements, only mercury (Hg)and bromine (Br) are liquids at room temperatures.Elements may
be simply divided as metals and non-metals depending upon their properties.
Metals usually show the following properties:
1. Most of the metals are sonorous, i.e. they make aringing sound when hit with an object.The
common examples of metals are sodium, potassium, zinc, copper, silver, gold, aluminium, iron,
etc.
2. They conduct heat and electricity
3. They are ductile
4. They are malleable
Non-metals usually show the following properties:-
1. They have low densities.About 80% of the elements are metals and theremaining 20% are
non-metals. All the metals aresolids except mercury which is a liquid. As wehave learnt above,
bromine is also liquid at roomtemperature but it is non-metal.
2. They are poor conductors of heat and electricity.
3. They are non- lustrous, non-sonorous and are not malleable.
Compounds:A compound is a pure substance made up of twoor more elements chemically combined with
one
another in a fixed proportion by mass e.g.,H2O is a compound made of two elements hydrogen
and oxygen chemically combined in a fixed proportion of 1:8 by mass(atomic mass of
H=1u,O=2u so we have2:16 which is simplified to 1:8).
Properties of Compounds
1. A chemical compound consists of two or more elements combined together in a fixed
proportion by mass.
2. The properties of a compound are entirely different from those of its constituent
elements.
3. The constituent elements of a compound cannot be separated by mechanical or physical
methods. We can say that the constituent elements of a compound cannot be separated
by physical methods.
4. A compound is a homogeneous substance.
5. A compound has a fixed melting point and boilingpoint.
6. The formation of a compound occurs because of a chemical reaction and is accompanied
by energy changes.
7. Since compounds are formed by the chemical combination of elements, they are also
called chemical compounds.
8. A mixture shows the properties of its constituents.
9. A mixture can be separated into its constituents by physical methods (like filtration,
evaporation, distillation, sublimation, mechanical separation, etc.)
10. A mixture does not have fixed melting point, boiling point, etc.
11. The properties of a compound are entirely different from those of its constituents.
12. A compound cannot be separated into its constituents by ordinary physical
methods.These can be separated by chemical or electrochemical reaction.
13. A compound has a fixed melting point, boiling point, etc.
SNO
1.
2.
3.
4.
5.
6.
MIXTURE
e.g.,H2O+SUGAR
A mixture can be separated into its
constituents by the physical
processes like filtration,
evaporation, sublimation etc.
A mixture shows the properties of
its constituents.
Energy is neither given out nor
absorbed during the formation of a
mixture
A mixture does not has a definite
formula because the composition
of a mixture is variable
A compound does not has a fixed
melting and boiling point
Mixtures:-
COMPOUND
H2O
A compound cannot be separated into its
constituents by any physical processes
A compound has the properties different
from its constituents.
Energy in the form of heat or light is either
given out or absorbed during the formation
of a compound.
A compound has a definite formula because
the composition of the constituents is fixed.
A compound has a fixed melting and boiling
point
Most of the materials that we come across in our daily life are mixtures. A mixture
contains more than one substances, elements or compounds.
A mixture may be solid, liquid or gas. Mixture is made up of two or more substances.
The substances which make a mixture are called constituents or components.
For example, lemonade (nimbupani) is a mixture of water, lemon juice, sugar and salt.
When we drink it, we get the sour taste of lemon, salty taste of salt and sweet taste of
sugar. Moreover, since it contains water also, it quenches our thirst like water.
A mixture can be separated by physical methods into its two or more pure substances.
For example, Sodium chloride dissolved in water can be separated from water by the
physical process of evaporation.
Types of Mixtures
Mixtures are of two types:
Homogeneous mixtures and Heterogeneous mixtures
Homogeneous Mixtures: -A mixture in which different constituents is mixed
uniformly.
Homogeneous mixtures have the same composition throughout the sample. It has no
visible boundaries of separation between various constituents. For example, salt
solution (sodium chloride dissolved in water), sugar solution (sugar dissolved in water),
all solutions, Alloys, Air etc.
Heterogeneous Mixtures: - mixtures in which different constituents are not mixed
uniformly.
Heterogeneous mixtures consist of two or more parts (called phases) which have
different compositions. It has visible boundaries of separation between the various
constituents. For example, un-dissolved sugar (solid phase) in sugar solution (liquid
phase), mixture of Iron and Sulphur etc.
Solutions, suspension and colloid
What is a solution?
A homogeneous mixture of two or more substances is called solution
The lemonade, sharbat, coke, pepsi, etc. are all examples of solution. The substances making up
the solution are called components of the solution. Solution is generally made up of two
components:(i) solute
(ii) solvent
Solvent:-A component which is present in large amount is called solvent ,it dissolves the other
component in itself.
Solute:-The component which is present in lesser amount is called solute, it is that component of
solution which dissolves in solvent..
Thus, a solute is a substance which dissolves and the solvent is a substance in which dissolution
takes place. For example, if a crystal of sugar is dropped into a beaker of water, it dissolves to
from a solution. In this case, sugar is solute and water is solvent.
Sugar + Water =Solution of sugar in water( sugar is the solute and water is the solvent).
These solution are also called true solutions
because the particles of solutions have very small size (less then 10-9 m or 1nm or 10-7cm).
Types of solution on the basis of states of solute and solvent
1. 1.Solution of solid in a solid - e.g., Alloys(An important alloy, brass containing
approximately 70% copper and approximately 30% zinc contains zinc as solute and copper
as solvent),) Mixtures of silver and gold and copper and gold are common examples of solid
in solid solution.
2. Solution of solid in a liquid - e.g., sugar solution, salt solution, Tincture of iodine
I2(solid)+alcohol(liquid).
3. Solution of liquid in a liquid - e.g., vinegar which is used as preservative and is also
added in Chinese foods is an example of liquid in liquid solution. It has acetic acid dissolved
in water.
4. Solution of gas in a liquid-e.g, aerated drink.
5. Solution of gas in gas-e.g., Air is mixture of gas in gas solution. It is a homogeneous
mixture of mainly two components: oxygen (20%) and nitrogen (78%). The other gases are
present in very small quantities. This is an example of gaseous solution.
Metal Alloys:Alloys are homogeneous mixture of two or more metals. These cannot be separated into their
components by physical methods. However, these are considered as mixture because these show
the properties of its constituents and can have variable composition.
For example:Brass is a mixture of copper and zinc. Stainless steel used for making utensils is a mixture of iron,
chromium and nickel.Bronze is a mixture of copper and tin and it is also commonly used for
making utensils, statues, etc.
Review Questions
1. Classify the following as physical or chemical changes:
a) Cutting of trees.
b) Melting of butter in a pan
c) Boiling of water to form steam.
d) Passing of electric current, through water and the water breaking down into H2 & O2
gases.
e) Dissolving common salt in water.
f) Making fruit salad with raw fruits.
g) Burning of paper, wood etc.
2. Which of the
i.
ii.
iii.
iv.
v.
vi.
vii.
following is chemical change?
Growth of a plant
Rusting of iron
Mixing of iron fillings and sand
Cooking of food
Digestion of food
Freezing of water
Burning of a candle.
3. Give the differences between elements and compounds.
4. List two points of differences between homogeneous and heterogeneous mixtures.
5. Which of the following are pure substances and which of them are mixtures?
Ice, Milk, Hydrocholoric acid, Calcium oxide, Mercury, Brick, Wood, Air, Salt,
Water, Alum, Sugar, Soil, Sea water, Air, Coal, Soda-water
6. Classify the following into elements and compounds:
H2O, He, Cl2 , CO, Co, Iron, Iron sulphide, Sulphur, Chalk, Washing soda,
Sodium, Carbon, Urea, Zinc, washing soda, graphite, nickel
7. Classify the following materials as homogeneous mixtures and heterogeneous mixtures:
Soda-water, Wood, Air, Soil, Vinegar, Alcohol and water mixture, Petrol and
water mixture, Chalk and water mixture, Sugar and water mixture, Copper
sulphate solution.
8. A substance X on heating gives y and z .What is X? An element, a compound or a mixture.
9. Classify the following into elements, compounds and mixtures:
i. Sodium, Soil, Sugar solution, Silver, Calcium carbonate, Tin, Silicon, Coal, Air,
Soap, Methane, Carbon dioxide , Blood
10. Air contains specified proportions of oxygen (21%) and nitrogen (78%). Still it is considered
to be a mixture. Explain why?
Review Questions are to be solved in Chemistry Note book and submitted on following dates
Submission Dates:
IX A: Day 6 (Thursday - 12th July)
IX B: Day 1 (Friday - 13th July)
IX C: Day 2 (Monday - 16th July)
IX D: Day 2 (Monday - 16th July)
Biology