Ch.2.3

Question 1

Water is ___________ for life on Earth.

Answer 1

Essential.

Question 2

Humans can survive up to several weeks without food. However, without water, one will likely __________ within a ___________ ___________.

Answer 2

die, few days.

Question 3

Only some forms of life contain water.

True/ false?

Answer 3

False.

Question 4

Give 5 ways of how we use water in many ways in daily life.

Answer 4

Washing, cooking, taking a shower, crop irrigation, creating paper and clothes

Question 5

In some parts of the world, people do not have tap water. They use natural water directly from __________, _________, _______ or _______.

Answer 5

Streams, rivers, ponds, wells.

Question 6

Natural water contains many kinds of impurities:

* Some of them such as leaves and sand are \_\_\_\_\_\_\_\_\_\_\_ in water
* Some impurities are \_\_\_\_\_\_\_\_\_\_\_ in water, eg salt
* Natural water also contain \_\_\_\_\_\_\_\_\_\_\_\_\_\_

Answer 6

Insoluble, soluble, microorganisms

Question 7

Microorganisms are too small to see with the naked eye but we can observe them with the help of a ________________.

Answer 7

Microscope.

Question 8

__________ and _________ are two microorganisms often found in natural water.

Answer 8

Amoeba, E. coli.

Question 9

Some microorganisms are harmful to us. They may cause _____________ diseases and other diseases such as ______________ and ____________.

Answer 9

Diarrhoeal, typhoid, chlolera

Question 10

E. coli in water or food often cause ___________ diseases.

Answer 10

Diarrhoeal.

Question 11

What are the three methods of water purification?

Answer 11

Sedimentation, distillation and filtration.

Question 12

Sedimentation can remove __________________.

Answer 12

Large insoluble impurities.

Question 13

During sedimentation, the large and heavy insoluble impurities sink to the _____________ of the container and form a layer of ___________.

Answer 13

Bottom, sediment.

Question 14

After sedimentation, the water above the sediment becomes ___________. However, some _____ ________ _____ are still suspended in it.

Answer 14

Clearer, small insoluble impurities.

Question 15

We can remove __________ _________ __________ and __________ __________ _________ in water by filtration.

Answer 15

Small insoluble impurities, large insoluble impurities.

Question 16

___________ ___________ and _________ __________ are commonly used filters in the laboratory.

Answer 16

Filter columns, filter papers.

Question 17

Filter paper has many ________ ___________.

Answer 17

Tiny pores.

Question 18

The small insoluble impurities are ___________ than the pores of a filter paper. Thus, these impurities cannot pass through the pores and are ___________ by the filter paper.

Answer 18

Larger, trapped.

Question 19

The small insoluble impurities trapped in the pores of a filter paper are called ___________.

Answer 19

Residue.

Question 20

The liquid that passes through the filter paper is called _________.

Answer 20

Filtrate.

Question 21

On the other hand, ____________ and _____________ __________ (eg salt) are much smaller than the pores of the filter paper. Hence, they pass through the filter paper.

Answer 21

Microorganisms, soluble impurities.

Question 22

Filtration can be used to remove _________ and _________________________ from water.

Answer 22

Large, small insoluble impurities.

Question 23

Filtration is used in some ___________ _________ ___________ for removing impurities from tap water.

Answer 23

household water filters.

Question 24

In distillation, water _________ and changes to ___________.

Answer 24

Boils, steam.

Question 25

When water boils to steam, ________________ in water are killed by the high temperature. Other ___________ in water will be left behind.

Answer 25

Microorganisms, impurities.

Question 26

During distillation, the steam condenses back to water upon cooling in the ________________.

Answer 26

Condenser.

Question 27

The water collected after distillation is called __________ ________.

Answer 27

Distilled water.

Question 28

Distillation removes:
1.
2.
3.
4.

Answer 28

Large insoluble impurities, small insoluble impurities, soluble impurities, microorganisms.