Class X

Science

Physics- 1/5/20 to 10/5/20

1. Copy the following notes in your physics register.

SOURCES OF ENERGY INTRODUCTION

Energy comes in different forms and energy can only be converted from one form to another. For

example if we drop a plate from a height, the potential energy of the plate is converted mostly to

sound energy when it hits the ground.

If we light a candle, the process is highly exothermic so that the chemical energy of the wax is

converted into heat energy and light energy on burning.

A Good Source of Energy would be one

Which has high calorific value.

Be easily accessible.

be easy to store and transport

Be economical.

Intermediate Ignition temperature.

Eco-friendly.

Less combustible

Conventional Source of Energy

Fossil fuels Fuels developed from the fossils. E.g. Coal & Petroleum.

Formed over millions of years ago have only limited reserves

These are non-renewable source of energy

Disadvantages of Burning Fossil Fuel Creates air pollution

Oxides of Carbon, Nitrogen, and Sulphur (acidic in nature) cause Air pollution & Acid rain & green-

house effect.

Thermal Power Plant In thermal power plant coal or oil is burnt to produce heat energy and this heat is used to boil water in

a reservoir. The boil water in turn produces steam and steam at high pressure is used to run the

turbine which in turn rotates the coil of the generator

Hydro Power Plant Hydro-power Plants convert the potential energy of falling water into Electricity since there are few

water-falls which could be served as a source of potential energy, hence this is the reason, a large

number of dams are built all over the world.

Around 25% of our country’s energy requirement is met by Hydro Power Plants

Dams are constructed to :

Prevent flooding of river; provide water for irrigation & to generate hydroelectricity.

Disadvantages of construction of Big Dams

1. Submerging/Loss of large variety of Flora fauna and human settlements& rotting of submerged

vegetation release greenhouse gas ( ).

2. They pose dangers of earthquakes, landslides etc.

Improvements in the Technology for using Conventional sources of

energy :

Biomass is Agricultural & animal wastes that can be used as a fuel. E.g. of Biomass – Firewood, cattle

dung, sewage, dry leaves, stems.

Normally biomass has low calorific value & produce lot of smoke when they are burnt. Their

efficiency as a good fuel has been increased tremendously with the application of technology. For

e.g. cow dung becomes efficient & cheap good fuel in a Bio-gas plant.

Charcoal is better fuel than wood because it does not contain water & other volatile material which

are present in wood.

Charcoal burns without smoke, flames & has high calorific value.

Biogas

Bio-gas is an excellent fuel & contains 75% of Methane ( ).It burns without smoke, leaves no

residues like ash, with high heat capacity.

Bio-gas is produced by anaerobic decomposition of the slurry (cow dung + water mixture) by

microbes. This process is applied in a Bio gas plant.

Biogas is a mixture of methane, carbon dioxide, hydrogen and hydrogen sulphide. The major

constituent of biogas is methane.

Biogas is produced by the anaerobic degradation of animal wastes like cow-dung or plant

wastes in the presence of water.

Biogas Plant (Fixed Dome Type)

The biogas plant has a dome-like structure built with bricks. Slurry of cow-dung and water is made in the

mixing tank from where it is fed into the digester. The digester is a sealed chamber in which there is no

oxygen. Anaerobic micro-organisms that do not require oxygen decompose or break down complex

compounds of the cow-dung slurry. It takes a few days for the decomposition process to be complete

and generate gases.

The Bio-gas is stored in the gas tank from which they are drawn through pipes for use in a Bio-gas plant.

Bio gas is used for lighting, cooking in the rural areas. While the slurry left behind is used as excellent

manure, rich in nitrogen and phosphorous. The large scale use of Bio-wastes & sewage material provide a

safe and efficient method of waste-disposal besides supplying energy and manure.

Wind Energy

Unequal heating of the landmass and water bodies by solar radiation generates air movement &

causes winds to blow. This kinetic energy of the wind can be used to do work.

This energy is utilized to lift water from the well & to generate electricity in the wind mill.

Actually the rotatory motion of the windmill is used to turn the rotor of the turbine which then

generates electricity through Dynamo.

The output of a single windmill is quite small so a number of windmills are erected over a large

area – called wind energy farm.

India Ranked Fifth in the world in harnessing wind energy for the production of electricity. It is

estimated that nearly 45,000 MW of electric power can be generated if India’s wind potential is

fully exploited.

The minimum wind speed for wind mill to serve as a source of energy is 15 Km/hr

Advantages of Wind Energy

1. Eco friendly

2. Efficient source of renewable energy.

3. No recurring expenses for production of electricity

Limitations of Wind Energy

1. Wind energy farms need large area of land

2. Difficulty in getting regular wind speed of 15-20 Km/hr

3. Initial cost of establishing wind energy farm is very high.

4. High level of maintenance of blades of wind mill.

Non-Conventional Sources of Energy

Solar Energy: The energy emitted by the sun in form of heat and light is called solar energy.

Solar Energy Devices

A large number of devices that utilize solar energy directly like :

(i) Solar Cooker

(ii) Solar furnaces

(iii) Solar cells

(iv) Solar water heaters

Solar Heating Devices

Use black painted surface because black surface absorbs more heat as compared to white or other

surface.

Use of glass plate because it allows shorter wave lengths infrared radiations to enter through it but

doesn’t allow the infrared radiations to exit through it, causing more green House effect that

results in increase in temperature.

SOLAR COOKER Box Type Solar Cooker

It consists of a rectangular box which is made up of material such as plastic or wood.

Box is covered with black sheet and its inner walls are painted black to increase heat absorption.

Solar cookers are covered with glass plate and have mirrors to focus the rays of the sun and

achieve a higher temperature.

Advantages of Solar Cooker

1. Use energy which is available in plenty (Solar Energy).

2. Is pollution free

3. Nutritional value of food is ppreserved.

4. Economical

Disadvantages of Solar Cooker

(i). Cannot be used for frying or baking purpose

(ii). Food cannot be cooked at night or on a cloudy day.

(iii). Direction of reflector of solar heating has to be changed from time to

time to keep it facing the sun.

SOLAR CELLS

Solar cells are device that convert solar energy into electricity.

Develops a voltage of 0.5 – IV and can produce about 0.7 W of electricity.

Advantages of Solar Cell

1. Require a little maintenance

2. Have no moving part.

3. Can be set up in remote areas.

4. Environment – friendly i.e. do not cause pollution.

Disadvantage of Solar Cells

1. It requires high cost

2. Efficiency is low

3. Initial cost of installation is quite high.

Uses of Solar Cell

1. Used in calculators, watches etc.

2. Used in artificial satellites and space probes.

3. It is used in radio or wireless transmission system.

SOLAR PANEL

A large number of Solar Cells connected to each other in an arrangement is called solar panel.

Material used for Making Solar Cells

Silicon

Silver is used for inter connection of cells.

ENERGY FROM THE SEA OR OCEAN: The energy from the sea is available in the following forms:

(i) Energy of sea waves

(ii) Tidal energy

iii) Ocean Thermal Energy.

(i) Energy of Sea Waves

The waves are generated by the strong winds that blow across the sea.

The kinetic energy of this moving water rotates the turbine of a generator

When strong winds stop blowing, the generator stops producing electricity

(ii) Tidal Energy

The tidal energy possessed by water during tides.

The tides are caused due to gravitational force of attraction exerted by the moon on the water of

the ocean.

This form of energy is harnessed by constructing a dam across a narrow opening to the sea.

A turbine fixed at the opening of the dam converts tidal energy to electricity.

(iii) Ocean Thermal Energy

The power plants used to harness the ocean thermal energy is known as “Ocean Thermal Energy

Conversion Plant” (OTEC)

Temperature difference between surface water and water at the depth of 2km should be 20°C or

more.

The warm surface water is used to boil ammonia (liquid)

The vapours of the liquid are used to run the turbine of generator.

The cold water (from deeper layers) is pumped up to condense the vapour into liquid.

Geothermal Energy

1. Energy stored as heat inside the earth

2. The steam of underground water is taken out by sinking pipes through holes drilled in the earth’s crust.

The steam under high pressure is used to rotate the turbines of the generator to produce electricity.

NUCLEAR ENERGY

Nuclear energy is the energy which is stored in the nucleus of an atom.

Nuclear energy is of two types

1. Nuclear fission nucleus of a heavy atom (Uranium) when bombarded with low

energy neutron split (break down) into lighter nuclei and huge amount of energy is released

2. Nuclear Fusion When two lighter nuclei join up to form heavy nucleus and tremendous amount

of energy is released.

Nuclear fission process is utilized in nuclear reactors to produce electricity.

Major Nuclear power plants : Tarapur, Rana Pratap Sagar, Kalpakkam.

Advantages of Nuclear Energy

1. Large amount of energy is released.

2. In nuclear power plant, the nuclear fuel is inserted once to get energy over a long period of time.

Disadvantages of Nuclear Energy

1. High cost of installation.

2. Environmental contamination may occur due to improper nuclear waste disposal.

How long will energy source last: Continuous use of non-renewable source of energy is a matter of

concern because ultimately the deposit of these sources will be completely finished on the other hand

renewable sources of energy will last forever e.g. sun as a source of energy will be available for a very

long period of time

2. Attempt the following questions on A4 size sheets for portfolio:

LIGHT – REFLECTION AND REFRACTION

1. List four characteristics of the images formed by plane mirrors.

2. Draw a ray diagram to show the path of the reflected ray corresponding to an incident ray which is

directed parallel to the principal axis of a convex mirror. Mark on it the angle of incidence and the

angle of reflection

3. A spherical mirror produces an image of magnification -1 on a screen placed at a distance of

50cm from the mirror.

(a) Write the type of mirror.

(b) Find the distance of the image from the object.

(c) What is the focal length of the mirror?

(d) Draw the ray diagram to show the image formation in this case.

4. State the laws of refraction of light. If the speed of light in vacuum is 3*108 ms-1, find the speed

of light in a medium of absolute refractive index 1.5.

5. Which phenomenon is responsible for making the path of light visible?

6. Define Reflection of Light? State the laws of Reflection of Light?

7. What happens when a ray of light strikes the rectangular glass slab? Show with the help of

relevant diagram?

8. The power of the lens is -4.0D. What is the nature of this lens?

9. Which type of mirror is used to give erect and enlarged image of an object?

10. Draw the ray diagram and also state the position, the relative size and the nature of image formed

by a concave mirror when the object is placed at the Centre of curvature of the mirror.

11. It is desired to obtain an erect image of an object, using concave mirror of focal length of 12 cm.

(i) What should be the range of distance of an object placed in front of the mirror?

(ii) Will the image be smaller or larger than the object? Draw ray diagram to show the formation of

image in this case.

(iii) Where will the image of this object be, if it is placed 6 cm in front of the mirror? Draw ray

diagram for this situation to justify your answer.

Show the position of pole, principal focus and the Centre of curvature in the ray diagram.

12. A student has three concave mirrors A, B and C of focal lengths 20 cm, 15 cm and 10 cm

respectively. For each concave mirror he performs the experiment of image formation for three

values of object distance of 30 cm, 10 cm and 20 cm.

Giving reason answer the following:

(a) For the three object distances, identify the mirror which will form an image equal in size to that of object. Find

at least one value of object distance.

(b) Out of the three mirrors, identify the mirror which would be preferred to be used for shaving purpose.

(c) For the mirror B, draw ray diagram for image formation for any two given values of object distance.

13. An object is placed at infinity from a concave mirror of focal length 10 cm. Find the position

and nature of image formed. Draw a ray diagram to show the formation of image. (Not to scale)

14. A divergent lens has a focal length of 30 cm. At what distance should an object of height 5 cm

from the optical Centre of the lens be placed so that its image is formed 15 cm away from the

lens? Find the size of the image also.

Draw a ray diagram to show the formation of image in the above situation

15. A converging lens forms a real and inverted image of an object at a distance of 100 cm from it.

Where an object should be placed in front of the lens, so that the size of the image is twice the

size of the object? Also, calculate the power of a lens.

State laws of refraction.

Biology – 11/5/20 to 20/5/20

1. Complete the NCERT Questions of Life Processes in your

Biology notebook.

2. Write down the following notes of Control and Coordination in

your notebook after the questions of Life Processes.

Living organisms respond to various stimuli like heat, light,

cold, touch, pressure etc.

Example : Withdrawal of hand on touching a hot object.

Control and Coordination in Animals

It is brought about in all animals with the help of two main

systems

(a) Nervous System

(b) Endocrine System

Nervous System : Consists of Brain, Spinal network and

a huge network of nerves.

Functions

(i) To receive the information from environment

(ii) To receive the information from various body

parts.(Stimuli Response)

(iii) To act accordingly through muscles and glands.

Stimulus : Any change in environment to which the

organisms respond is called stimulus.

E.g., touching a hot plate.

Response : The reaction of our body to a stimulus. E.g.

withdrawal of our hand on touching hot plate.

Coordination- The working together of various organs of the

body of an organism in a proper manner to produce appropriate

reaction to a stimulus is called coordination.

Receptors : Are specialized tips of some nerve cells that

detect the information from the environment.

Receptors are sense Organs

Neuron : It is the structural and functional unit of nervous system.

Neurons (also known as neurones, nerve cells and nerve

fibres) are electrically excitable cells in the nervous system that

function to process and transmit information. In vertebrate

animals, neurons are the core components of the brain, spinal

cord and peripheral nerves.

The primary components of the neuron are the soma (cell body),

the axon (a long slender projection that conducts electrical

impulses away from the cell body), dendrites (tree-like

structures that receive messages from other neurons), and

synapses (specialized junctions between neurons).

The axon (nerve fibre) transmits electrical signals from the cell

body. The dendrites are

branching fibres that receive electrical signals from other neurons.

The shape of a neuron is

determined by the job it does.

Synapse :The point of contact between the terminal branches of

axon of one neuron with the dendrite of another neuron is called

synapse.

REFLEX ACTION

Reflex action is an automatic response of the body to a

stimulus. e.g. withdrawal of hand, knee jerk etc. on touching a

hot plate.

Reflex arc : The pathway taken by nerve impulses in a reflex

action is called reflex arc.

Voluntary means it is under the control of a person (e.g. writing)

Involuntary means it is not under the control of a person. (e.g.

heartbeat)

Mechanism of Reflex action: A reflex mechanism involves a

receptor organ, an effector organ, and some type of

communication network. When a sensory receptor is stimulated,

signals pass from it along a sensory neuron to the spinal cord.

The message travels out of the spinal cord along a motor neuron

to the effector organ (e.g., a muscle or a gland), which shows the

response. Such a pathway is called a reflex arc. In most cases,

however, the basic physiological mechanism behind a reflex is

more complicated than the reflex arc theory would suggest.

Additional nerve cells capable of communicating with other parts of

the body(beyond the receptor and effector) are present in reflex

circuits.

HUMAN NERVOUS SYSTEM : The nervous system of

vertebrates (including humans) is divided into the central nervous

system (CNS) and the peripheral nervous system (PNS).

The (CNS) is the major division, and consists of the brain and

the spinal cord. The spinal canal contains the spinal cord, while

the cranial cavity contains the brain.

Human Brain : It is enclosed in cranium (brain box) and is protected

by

cerebrospinal fluid which acts as a shock absorber. Human brain

has three major parts or regions :

(a) Fore-brain (b) Mid Brain (c) Hind Brain.

(a) Fore-brain(CEREBRUM)

Most complex/specialized part of the brain is Cerebrum or the

forebrain. Functions

1. Thinking part of the brain

2. Control the voluntary actions.

3. Store information(Memory)

4. Centre associated with HUNGER

5. Receives sensory impulses from various body parts and integrates it

(b) Mid Brain

It connects the fore-brain with the hind-brain. It is the portion of the

central nervous system associated with vision, hearing, motor

control, sleep/wake, arousal (alertness), and temperature

regulation.

(c) Hind-Brain

Brain : The human brain is the command centre for the human

nervous system. It receives input from the sensory organs and

sends output to the muscles. The human brain has the same

basic structure as other mammal brains, but is larger in relation

to body size than any other brains.

Brain is protected by a fluid called cerebrospinal fluid which

acts as shock absorber. It has several layers called

MENINGES.

Spinal Cord : Spinal Cord is enclosed in Vertebral column.

HORMONES are chemical compounds which help to coordinate

growth, development and responses to the environment.

Plant Hormones :

Main plant hormones are :

(a) Auxin: Auxin is a plant hormone produced in the stem tip

that promotes cell elongation.

(b) Gibberellin : Gibberellins (GAs) are plant hormones that

regulate growth and influence various developmental processes,

including stem elongation, germination, flowering, enzyme

induction, and leaf and fruit senescence(falling).

(c) Cytokinins : Cytokinins (CK) are a class of plant growth

substances (phytohormones) that promote cell division, or

cytokinesis, in plant roots and shoots. They are involved

primarily in cell growth and differentiation, but also affect apical

dominance, axillary bud growth, and leaf senescence.

(d) Abscisic acid :Inhibits growth, cause wilting of leaves.

(Stress hormone).It promotes the closing of stomata (during

adverse rough condition) their by reducing the water loss.

HORMONES IN ANIMALS

Hormones : Hormones are the chemical substances secreted by

the endocrine glands and transmitted by the blood to the tissues

on which it has a specific effect.

S. No. Hormone Endocrin

e Gland

Location Function

1. Thyroxine Thyroid Neck/Throat Region

Regulation of metabolism of

carbohydrates,

fats and

proteins.

2. Growth Hormone

Pituitary

(Maste

r

Gland)

Mid-brain Regulates

growth and development.

3. Adrenalin

e

Adrenal Above Both Kidney

Regulation (increasing)

of blood pressure,

heart beat, carbohydrate

metabolism(duri

n

g emergency).

4. Insulin Pancrea

s

Below Stomach

Reduces and regulates

blood sugar level.

5. Sex Hormone

s

Testosteron e (in Males) Oestrogen (in Females)

Testes (in

Males) Ovaries

(in

Females

)

Genital/Lowe r

Abdomen Area

Changes associated

with puberty

(sexual

maturity)

Iodised Salt is Necessary because thyroid gland needs iodine

to make thyroxine which helps in regulating the metabolism of

carbohydrates, fats and proteins. Deficiency of iodine causes a

disease called goitre.

EXAMPLE :

Diabetes

Cause : It is due to deficiency of Insulin hormone secreted by

Pancreas that is responsible to lower/control the blood sugar

levels.

Treatment : Common diabetes can be controlled by medicine

but in severe cases. Injections of insulin hormone are given to

the patients.

Feedback Mechanism

The excess or deficiency of hormones has a harmful effect on our

body. Feedback mechanism makes sure that hormones are

secreted in precise quantities and at right time.

3. Complete the given questionnaire on A4 size sheets for portfolio.

LIFE PROCESSES (NUTRITION)

One Mark Questions

1 Give the appropriate terms to the following statements

a. Any substance taken into the body for purpose of providing nutrition.

b. Conversion of complex food particles into simpler food particles in presence of enzymes.

2 Name the enzymes found in the pancreatic juice.

3 What are the raw materials used in photosynthesis.

4 What is the role of gastric HCl?

5 What is life process? Give some examples for life process?

6 Name the type of nutrition.

7 Name the type of nutrition

a. Fungi like bread mould, yeast, mushroom breakdown the food materials outside the body

and absorb it.

b. Cuscuta, lice and ticks derive nutrition from plants or animals without killing them

Two Marks Questions

8 How does Amoeba intake food? Briefly mention.

9 Which digestive secretion does not contain any enzyme but is very important in the process of

digestion. Comment on it.

10 a) What are the major events occurring during the process of photosynthesis?

b) Name the energy transformation taking place in the process of photosynthesis.

11 Write the name / terms associated with the following

a) the natural phenomenon involved in autotrophic nutrition

b) the organelle of the leaf in which photosynthesis takes place

c) the photosynthetic pigment which absorb light energy

d) the structures associated with vascular bundle

12 How is the small intestine designed to absorb food?

13 Leaves of a healthy potted plant were coated with Vaseline to block the stomata. Will this plant

remain healthy for long? State three reasons for your answer.

Three Mark Question

14 How are fat digested in our bodies? Where does this process take place?

15 Match the following pair of statements (associated with an experiment in photosynthesis) and place

them in the correct order in which they occur

Stages in starch test Reason

Wash leaf in water Kills leaf

Boil leaf in water Soften leaf

Cover with iodine solution Removes chlorophyll

Boil leaf in ethanol Inflammable (prevent fire)

Use of water bath Stain starch

16 What is peristalsis? Explain both mechanical as well as the chemical part of digestion of food in the

mouth of man.

17 Parwati collected his saliva and mixed it with liquid A in the test tube. In another test tube he took

only liquid A. After 10 minutes, she added a few drops of iodine solution in the mixture in the first

test tube. It did not show any colour but when she treated the other test tube with iodine, a blue black

colour appeared. Now answer–

a) What is the aim of this activity?

b) What is liquid A?

c) Why did the first test tube not shown any colour change with iodine while the second one did?

d) Which enzyme is responsible for such a result?

18 a) Explain the process of digestion of food in the stomach.

b) How passage of food from the stomach is regulated onwards?

c) Explain the process of fat digestion in the gut of man.

(RESPIRATION)

Very Short Answer question

1. Why do organisms need food?

2. How does food yield energy?

3. What is respiration?

4. What is a respiratory substrate?

5. Name a few respiratory substrates. Which of them is most commonly used?

6. Give the general equation for respiration. Which part of a plant is involved in the gaseous exchange?

7. How does gaseous exchange take place in the leaves?

8. How does exchange of gases take place in fish?

9. From where do the fish obtain their oxygen supply?

10. Which are the respiratory organs in man?

11. Where are the lungs in man situated?

12. Describe the structure of the lungs. Name the various parts of the respiratory tract?

13. What is the significance of respiration?

14. Write short notes on trachea. How does exchange of gases take place in the alveoli?

15. What is oxyhemoglobin and how is it formed?

16. How does carbon dioxide get transported in the blood?

17. What is inspiration (inhalation)?

18. What is expiration (exhalation)?

19. What is breathing?

20. Breathing and respiration are not synonymous. Why?

21. What is cellular respiration?

22. What are the major steps of cellular respiration?

23. What is anaerobic respiration?

24. Name two anaerobic. Where do you find anaerobic respiration in animals?

25. What are the types of anaerobic respiration?

26. Which type of respiration is more efficient- aerobic or anaerobic? Why?

Multiple Choice Questions

1. Raw material of respiration is

(a) Glucose and CO2(b) Glucose and O2(c) Glucose and fructose(d) Glucose and sucrose

2. Respiration differs from the process of combustion in the fact that

(a) All the energy stored in glucose in released at once due to combustion

(b) All energy stored in glucose is gradually released due to combustion

(c) Comparatively large quantity of energy is produced due to combustion

(d) The carbohydrates act as the combustion substance

3. Respiration is

(a) Anabolic process(b) Physical process(c) Catabolic process(d) Biophysical process

4. Respiration is

(a) Catabolic process that uses carbon dioxide, produces oxygen and converts released energy to ATP

(b) Anabolic process that uses oxygen and carbon dioxide to from ATP

(c) Anabolic process that uses oxygen produces carbon dioxide and converts released energy into ATP

(d) Catabolic process that uses oxygen produces carbon dioxide and converts released energy into ATP

5. Respiratory enzymes are located in

(a) Mitochondrial matrix (mitochondria)(b) outer-inner membrane space(c) Cristae(d) Outer membrane

6. Site of Glycolysis is

(a) Mitochondria (b) Cytoplasm (c) Endoplasmic Reticulum (d) Ribosomes

7. The cycle in which pyruvic acid is broken down in presence of oxygen is known as

(a) Glycolysis(b) Krebs cycle(c) Anaerobic respiration(d) None of the above

8. The end products of alcoholic fermentation are

(a) CO2 and O2(b) CO2 and C2H5 OH(c) O2 and C2H5 OH(d) CO2 and acetaldehyde

9. The end products of respiration in plant are

(a) CO2, H2O and energy (b) Starch and O2 (c) Sugar and O2 (d) H2O and energy

Chemistry – 21/5/20 to 30/5/20

Instructions for students

Compile the notes of chapter 2 (Acid, Base and salts) in chemistry notebook.

Questionnaire for Chapter 1 are given below that you all have to compile on A4 size sheet. Refer the

NCERT text book for activity based questions and for different reactions.

CHAPTER-2

ACIDS, BASES AND SALTS

1) Acids are sour in taste, turn blue litmus red, and dissolve in water to release H+ ions e.g. HCl, H2SO4,

HNO3 etc.

2) Bases are bitter in taste, have soapy touch, turn red litmus blue and give hydroxide ions in solution.

e.g. NaOH, KOH etc.

3) A salt is a compound which is formed by neutralization reaction between an acid and base.

e.g. sodium chloride.

Indicators – Indicators are substances which indicate the acidic or basic nature of the solution by their colour

change. The colour of some acid – base indicators in acidic and basic medium are given below

Chemical properties of acids: (refer NCERT book for general reaction).

i) Acids react with active metals to give hydrogen gas and salt.

Zn + H2SO4 ZnSO4 + H2

ii) Acids react with metal carbonate and metal hydrogen carbonate to give carbon dioxide, water and salt.

NaHCO3 +HCl NaCl + H2O + CO2

iii) Acids react with bases to give salt and water. This reaction is called as neutralization reaction.

NaOH + HCl NaCl +H2O

iv) Acids react with metals oxides to give salt and water. CuO + H2SO4 CuSO4 + H2O

6) Chemical properties of Bases: (refer NCERT book for general reaction).

i) Reaction with Metals - Certain reactive metals such as Zinc, Aluminium, and Tin react with alkali solutions

on heating and hydrogen gas is evolved.

2NaOH + Zn Na2ZnO2 +H2

ii) Reaction with acids -Bases react with acids to form salt and water.

KOH +HCl KCl +H2O iii) Reaction with Non -metallic oxides – These oxides are generally acidic in nature. They react with bases to

form salt and water.

2NaOH + CO2 Na2CO3 + H2O

PH Scale: The concentration of hydrogen ion in solution is expressed in terms of pH. The pH of a solution is

defined as the negative logarithm of hydrogen ion concentration in moles per liter.

pH = - log [H+] For water or neutral solutions, pH = 7 ; For acidic solutions, pH < 7; For basic solutions, pH > 7

8) Some Important Chemical Compounds:

Common Salt (NaCl): Sodium chloride is known as common salt. Its main source is sea water. It is also exists

in the form of rocks and is called rock salt. Common salt is an important component of our food. It is also used

for preparing sodium hydroxide, baking soda, washing soda etc.

a) SODIUM HYDROXIDE OR CAUSTIC SODA (NaOH)

It is prepared by passing electricity through an aqueous solution of sodium chloride also known as brine.

2NaCl (aq) + 2 H2O (l) 2NaOH (aq) + Cl2 (g) + H2 (g) This process is known as chlor-alkali

process. Properties:

1. It is white translucent solid.

2. Crystals of sodium hydroxide are deliquescent.

3. It is readily soluble in water and gives strong alkaline solution.

b) BLEACHING POWDER (CaOCl2)

Its chemical name is calcium oxychloride. It is prepared by passing chlorine gas through dry slaked lime.

Ca (OH) 2 + Cl2 CaOCl2 + H2O

Uses –

1. For bleaching cotton and linen in textile industry and wood pulp in paper industry

2. For disinfecting drinking water.

c) BAKING SODA (NaHCO3)

Chemical name is Sodium hydrogen carbonate. It is prepared by passing CO2 gas through brine solution saturated with ammonia.

NaCl + H2O +CO2 +NH3 NH4Cl + NaHCO3

Properties:

1. It is white crystalline solid and sparingly soluble in water at room temperature.

2. On heating it decomposes to give sodium carbonate and carbon dioxide.

3. It reacts with acids to give carbon dioxide gas.

4. It aqueous solution is weak alkaline due to hydrolysis.

Uses:

1. It is used in soda – acid fire extinguisher.

2. It acts as mild antiseptic and antacid.

3. It is used as a component of baking powder. In addition to sodium hydrogen carbonate baking soda contains

tartaric acid.

d) WASHING SODA (Na2CO3.10 H2O)

Chemical name is sodium carbonate decahydrate.

It is prepared by heating baking soda. Recrystallisation of sodium carbonate gives washing soda.

2NaHCO3 Na2CO3 +H2O +CO2

Na2CO3 +10 H2O Na2CO3.

10 H2O

Uses:

1. It is used for removing permanent hardness of water.

2. It is used in glass, soap and paper industries.

3. It can be used as a cleaning agent for domestic purposes.

e) PLASTER OF PARIS (CaSO4.1/2H2O)

Its chemical name is calcium sulphate hemihydrates. It is obtained by heating Gypsum upto 373K.

CaSO4.2H2O CaSO4.1/2H2O + 11/2H2O

On treatment with water it is again converted into gypsum and sets as a hard mass.

CaSO4.1/2H2O+11/2H2OCaSO4.2H2O

Uses:-

1. It is used by doctors for setting fractured bones.

2. It is used for making statues, models and other decorative materials.

Questionnaire of chapter 1

Chemical reactions and equation

Fill in the blanks:-

1. Addition of hydrogen in a substance in a reaction is known as reaction.

2. In a reaction two or more substances combine to form a new single substance.

3.Reactions in which heat is given out along with the products are called - reactions.

4.Reactions in which energy is absorbed are known as reactions.

5. When as element displaces another element from its compound, a reaction occurs.

6. Those reactions, in which two compounds react by an exchange of ions to form two new compounds, are

called reactions

7. Precipitation reactions produce salts.

8. Reduction is the of oxygen or gain of hydrogen.

9. The digestion of food in the body is an example of reaction.

10. The addition of oxygen to a substance is called .

11. When calcium carbonate is heated, it decomposes to give and .

True/ False:-

1. The number of atoms of each element is conserved in any chemical reaction.

2. Oxidation is the loss of electrons from a substance.

3. Reduction is the gain of electrons by a substance.

4.A complete chemical equation represents the reactants, products and their physical states symbolically.

5.A magnesium ribbon burns with a dazzling flame in air (oxygen) and changes into a white substance,

magnesium oxide.

6. Rusting is a double decomposition reaction.

7. The reaction between nitrogen and hydrogen to give ammonia is an example of a combination reaction.

8. Action of heat on ferrous sulphate is an example of decomposition reaction.

9. The formation of Na+ and CI- ions from sodium and chlorine is an example of a redox reaction.

Very Short Answer Questions:-

Question 1. Write a chemical equation when magnesium metal reacts with aqueous hydrochloric acid to

produce a solution of magnesium chloride and hydrogen gas.

Question 2. Can a combination reaction be redox reaction.

Question 3. Why do we apply paint on iron articles?

Question 4. What are the different types of reactions?

Question 5. What is a decomposition reaction ? Give example.

Question 6. Define displacement reaction.

Question 7. What happens when sodium reacts with water?

Question 8. Write the chemical equation and name the reaction when a solution of sodium chloride is mixed

with a solution of silver nitrate and a white precipitate of silver chloride is formed.

Question 9. Why does the colour of copper sulphate solution change, when an iron nail is dipped in it?

Question 10. Why is photosynthesis considered as an endothermic reaction?

Question 11. Potassium chlorate (KCIO3) on heating forms potassium chloride and oxygen. Write a balanced

equation for this reaction.

Question 12. Give an example of a chemical reaction characterized the change in temperature.

Question 13. What type of chemical reactions take place when:

a) Limestone is heating?

b) A magnesium wire is burnt in air?

c) Electricity is passed through water?

d)Ammonia and hydrogen chloride are mixed?

e)Silver bromide is exposed to sunlight?

Question 14. To balance a chemical equation, can we change the formula of either reactants or products?

Question 15. Why should a magnesium ribbon be cleaned before burning in air?

Question 16. If an of the following reactions occurs spontaneously, write the balanced net ionic equation. If

not, write no reaction&

a)Pb + Zn2+ Pb2+ + Zn

b)Fe + H+ Fe2+ + H2

c)Cu + Ag+ Cu2+ + Ag

d)Cr + Zn2+ Cr3+ + Zn

Question 17. Nickel (II) nitrate is prepared by heating nickel metal with liquid dinitrogen tetroxide. In addition

to the nitrate, gaseous nitrogen monoxide is formed. Write the balanced equation.

Question 18. Why is the amount of gas collected in one of the test tubes in electrolysis of water double of the

amount collected in the other? Name this gas.

Question 19. Write a balanced chemical equation with state symbols for the following reactions:-

i.Solution of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the

solution of sodium chloride.

ii.Sodium hydroxide solution (in water) reacts with hydrochloric acid solution (in water) to produce sodium

chloride solution and water.