Ch.2.4

Question 1

Name the three methods to kill microorganisms in water.

Answer 1

Chlorination, adding ozone, using ultraviolet light.

Question 2

We can kill the microorganisms in water quickly by adding _________ to it.

Answer 2

Chlorine.

Question 3

Chlorine can kill ________ _____________in water.

Answer 3

Most microorganisms.

Question 4

Adding chlorine to water to kill microorganisms is called __________.

Answer 4

Chlorination.

Question 5

Chlorination is used in many __________ ___________ _________ and some ____________ __________ to kill the microorganisms in water

Answer 5

Water treatment plants, swimming pools.

Question 6

However, chlorine is _________ and has an ___________ smell.

Answer 6

Toxic, irritating.

Question 7

If too much chlorine is added to water in swimming pools, it my irritate our _________ and __________.

Answer 7

Skin, eyes.

Question 8

Therefore, it is important to add the ____________ amount of chlorine to water to kill microorganisms.

Answer 8

Appropriate.

Question 9

Besides chlorine, ____________ is also widely used to kill microorganisms in water.

Answer 9

Ozone.

Question 10

Ozone is often used to sterilise the water in ______________ _______.

Answer 10

Swimming pools.

Question 11

Ozone is also used in some ____________ ___________ ________ for killing microorganisms in water

Answer 11

Water treatment works.

Question 12

Although ozone is more _____________ than chlorine, it has the following advantages over chlorine for water treatment:

        * Unlike chlorine, ozone does not have an \_\_\_\_\_\_\_\_\_\_ smell 
        * Ozone is more \_\_\_\_\_\_\_\_\_\_\_ than chlorine in killing microorganisms

Answer 12

Expensive, irritating, effective

Question 13

However, it is very important to control the amount of ozone added to water. _____________ ozone can cause ___________ and __________.

Answer 13

Inhaling, headache, vomiting.

Question 14

Ultraviolet light is commonly used in ______________ __________ ___________, ____________ _________ and ____________.

Answer 14

Portable water purifiers, drinking fountains, aquariums

Question 15

Ultraviolet light is not __________.

Answer 15

Toxic.

Question 16

Although fluoride cannot kill microorganisms, it can help prevent _________ _________.

Answer 16

Tooth decay.

Question 17

Fluoride is a common ingredient in _____________.

Answer 17

Toothpaste.

Question 18

In some ___________ __________ __________ around the world, fluoride is added to drinking water to help prevent tooth decay. This process is called _____________.

Answer 18

Water treatment plants, fluoridation.