Selina solutions for Concise Chemistry [English] Class 6 ICSE chapter 7 - Water [Latest edition]

Name:
Three major sources of natural water

Name:
 Four sources of surface water

Name:
Two underground sources of water. 

Answer the following questions in short: 
In which form is water present in the atmosphere? 

Answer the following questions in short: 
Which source of water contains the highest concentration of salt in it? 

Answer the following questions in short: 
Why is rainwater considered the purest form of natural water? 

What possible impurities does rainwater contain?

Answer the following questions in short: 
 What is water table? 

Answer the following questions in short:

Why is spring water pure enough for drinking but unsuitable for laboratory use?

Answer the following questions in short: 
Why the taste of spring water differs at different places? 

List three major impurities present in river water. 

Give the percentage of water in the following:
Rice and wheat grains

Give the percentage of water in the following:
Eggs

Give the percentage of water in the following:
Tomatoes 

Give the percentage of water in the following:
Bread

Give the percentage of water in the following:
Watermelon

What are the three states of water? 

Why are ice, liquid water, and steam considered to have the same chemical substance?

How is a cloud formed? 

What is water cycle? What is its importance? 

How Fog is formed?

How mist is formed?

How Dew is formed?

How frost is formed?

Name :
Two chemicals used to destroy germs present in water.

Name :
 Two diseases which spread through impure water. 

Name :
A chemical used for loading. 

Name :
Two substances which add taste to water.

Name :
Two household methods to get safe drinking water. 

Answer in brief: 
 Why is river water unfit for drinking?

Answer in brief: 
Why is tap water a mixture?

Answer in brief: 
What is mineral water?

Answer in brief: 
What is the purpose of adding bleaching powder to water supplied to the town? 

Answer in brief: 
How is chemically pure water obtained in the laboratory?

Answer in brief: 
How is water in the swimming pool kept free a germ? 

Define:
Sterilisation

Define:
Sedimentation

Define:
Loading

Define:
Aeration

What is potable water? List four characteristics of potable water.

Why is water important for plants and animals?

What are the three methods of removing germs from natural water? Explain.

Name the steps involved in the purification of drinking water supplied in cities and towns

What is the taste of distilled water? Why is it not potable? 

Give reasons
Ice floats on water

Give reasons
Marine life is able to survive in colder regions.

Give reasons
Water droplets can be seen outside a chilled water bottle

Why is water called a universal solvent?

Define:
Solute

Define:
Solvent

Define:
Solution

Define:
Saturated solutions

Define:
Unsaturated solutions

State two factors by which solubility of a solute in a solvent can be increased.

Why do aquatic animals die in boiled water? 

State three differences between water and air.

State four ways by which water can be conserved.

Explain the harvesting of water.

What are the three main causes of water pollution?

State the main steps to be taken to prevent water pollution. 

What are the causes of floods and drought?

State some of the ways in which you as an individual can conserve water.

Fill in the blank.
Water is a ______ solvent

Fill in the blank.
_________  is the purest form of natural water.

Fill in the blank.
Sand and dust are suspended _______  in water

Fill in the blank.
Seawater has a high concentration of _______.

Fill in the blank.
Water covers nearly ________ of the surface of the earth

Fill in the blank.
Evaporation of rainwater leaves _____residue.

Fill in the blank.
__________  is the chemical added to water to remove the tiny suspended particles.

Fill in the blank.
A _______ is a uniform mixture of a solute and a solvent.

Fill in the blank.
Ice, water, and steam have different physical states but are chemically __________.

Fill in the blank.
Boiling kills most of the ______ in the water.

Fill in the blanks.
The elements present in the molecules of water are ______ and _____.

Write True or False for the following statement.
Water is an element

Write True or False for the following statement.
Tap water does not contain dissolved impurities.

Write True or False for the following statement.
Alum is commonly used for removing suspended impurities

Write True or False for the following statement.
Distillation is a good method for purifying water for town supply

Tick (√) the correct alternative from the choice given for the following statement:
Water content in the human body is

Tick (√) the correct alternative from the choice given for the following statement:
The purest form of natural water is

Tick (√) the correct alternative from the choice given for the following statement:
When the water vapour changes into tiny droplets of water near the ground, it is called

Tick (√) the correct alternative from the choice given for the following statement:
Water is a

Tick (√) the correct alternative from the choice given for the following statement:
Common salt is obtained from sea water by

Tick (√) the correct alternative from the choice given for the following statement:
Jaundice affects

Tick (√) the correct alternative from the choice given for the following statement:
Chlorination of water is done

State the sources of water :
on the earth’s surface

State the sources of water :
below the earth’s surface

Give the importance of water in life processes

Give the importance of water in household purpose

Give the importance of water in Fire fighting

Give the importance of water in transportation.

Explain how water plays an important role in the Industry.

Explain how water plays an important role in Agriculture.

Give the occurrence of water in the three different states i.e. solid, liquid, and gaseous.

Draw a labelled diagram to show the change of state of water from solid-state to liquid state to the gaseous state starting from ice.

Explain the term water cycle. State the main points to show how water moves from the earth’s surface to the atmosphere and back to the earth’s surface as rain

Give a reason why water is considered a universal solvent.

Define:
Solute

Define:
Solvent

Define the term:
Solution with reference to the addition of sodium chloride to water

Draw a neat labelled diagram of the addition of copper sulphate to water. Label solute, solvent, and solution in the same.

From the following substances given below state which will form a solution in the same.
(a) sodium carbonate
(b) calcium carbonate
(c) charcoal powder
(d) sodium sulphate
(e) table salt
(f) powdered particles of lead from a lead pencil
(g) iron powder
(h) copper filings
(i) sand particles
(j) honey

Name two gases which are soluble in water

Name two gases which are insoluble in water.

If ‘X’ g. of potassium nitrate is added to 100 g. of water at 60°C and the salt dissolves completely then :

(a) is ‘X’ g. the solubility of potassium nitrate at 60°C.
(b) is the solution formed – saturated or unsaturated
(c) if on addition ‘X’ + ‘Y’ g. of potassium nitrate to the same amount of water at the same temperature and the solute now just remains behind after stirring then –
(d) is the solution now – saturated or unsaturated
(e) is ‘X’ + ‘Y’ g. the solubility of potassium nitrate.

State whether the following statement is true or false. If false write the correct statement.
Solubility of most solids – decreases with increase in temperature

State whether the following statement is true or false. If false write the correct statement.
Distilled water is potable water.

State whether the following statement is true or false. If false write the correct statement.
The process to remove germs in water is also called sterilization

Differentiate between chemical pollution and thermal pollution.

State some important steps to avoid pollution of water.

State what is meant by the term ‘conservation of water’.
State a few water-saving methods, which may be used in the home to conserve water.

Give a reason why :
Conservation of water is essential in spite of the fact that three fourth of the earth’s surface is covered by water.

Give a reason why :
Polluted water causes disease.

Give a reason why :
Drip irrigation helps in the conservation of water.

Complete the statement by filling in the blanks with the correct words.

________ is the purest form of water. It may dissolve gases like ________forming weak acids.

(sea water/ lake water/rain water ; chlorine/ammonia/carbon dioxide)

Complete the statement by filling in the blanks with the correct words.

Water generates ______in hydroelectric power stations and ________in boilers for industrial applications.

(carbon dioxide/steam/heat/electricity)

Complete the statement by filling in the blanks with the correct words.

Water is added to the atmosphere by _____________and _____________.

(burning of fossil fuels/condensation of vapour/ respiration by living organisms/photosynthesis)

Complete the statement by filling in the blanks with the correct words.

If potassium nitrate is added to water in a beaker to give a homogeneous mixture, then potassium nitrate is referred to as the __________, water as the __________, and the homogeneous mixture as the _______.

(solution/ solute/solvent/saturated solution)

Complete the statement by filling in the blank with the correct words.

Water fit for human consumption and drinking purposes is called ____________.

State whether the following statement is true or false. If false, write the correct statement.

Sea water contains salts of calcium and magnesium.

State whether the following statement is true or false. If false, write the correct statement.

Water finds application as a means of transporting goods.

State whether the following statement is true or false. If false, write the correct statement.

On boiling water exists in the liquid state.

State whether the following statement is true or false. If false, write the correct statement.

Respiration uses up water from the atmosphere.

State whether the following statement is true or false. If false, write the correct statement.

Sodium carbonate and sodium sulphate do not form an aqueous solution.

State whether the following statement is true or false. If false, write the correct statement.

If ‘X’ g. of solute is added to 100 g. of water at t°C and the solution formed is a saturated solution, then ‘X’ g. is the solubility of the solute.

State whether the following statement is true or false. If false, write the correct statement.

Purification of water is carried out to remove – dissolved gases e.g. carbon dioxide and dissolved minerals like magnesium salts.

State whether the following statement is true or false. If false, write the correct statement.

Water from rivers and lakes is – potable water.

State whether the following statement is true or false. If false, write the correct statement.

Chemical pollutants include a metallic salt solution of mercury and lead.

Match the statements in List I, 1-10 with their correct answer in List II, A to J.

Explain the meaning of the following term:

Rainwater harvesting

Explain the meaning of the following term:

Drip irrigation in agriculture

Explain the meaning of the following term:

Saturated solution

Explain the meaning of the following term:

Conservation of water

Explain the meaning of the following term:

The gaseous state of water in the air

Name the following

A chemical used during chlorination of water.

Name the following

An agricultural pollutant in water

Name the following

A solid, ‘natural form of water.

Name the following

The natural process by which circulation of water takes place from the earth’s surface to the atmosphere and back to the earth’s surface.

Name the following

The liquid or medium of dissolution which allows the solute to dissolve in it.