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F2 IS EXP 02 Answers

1st Term EXP 02 Submission date：_____________ Name：______________________ Class & no.：2 _________(     )

Experiment 7.1C: Comparing比較 the oxygen and

carbon dioxide content of breathed air未經呼吸的空氣

and unbreathed air呼出的空氣 (P.9-11)

Objective: To compare the oxygen and carbon dioxide content of breathed / unbreathed air

and unbreathed / breathed air.

Results結果:

B. Comparing the oxygen content

	Breathed air	Unbreathed air
Time taken for burning splint to go out (s)	(shorter time)	(longer time)

C. Comparing the carbon dioxide content

	Breathed air	Unbreathed air
Colour of hydrogencarbonate indicator after shaking	yellow	red

Discussion結論:

(a)    Which one contains more oxygen, breathed air or unbreathed air? unbreathed air

(b)   Explain how you get your answer in (a)?

The splint burns for a longer time in the jar which contains more oxygen. (OR other reasonable answers)

Conclusion結論:

Ø   Breathed air contains less oxygen than unbreathed air.

Ø   Breathed air contains more carbon dioxide than unbreathed air

Experiment 7.1D: Compare the temperature of breathed air and unbreathed air

Objective:      To compare the temperature of breathed air and unbreathed air.

Results:

	Breathed air	Unbreathed air
Temperature (oC)	(higher)	(lower)

Conclusion:

Ø   The temperature of breathed air is higher than that of unbreathed air.

Experiment 7.1E: Compare the water vapour content (水蒸汽) of breathed air and unbreathed air

Objective:      To compare the water vapour content of breathed air and unbreathed air.

Results:

	Under breathing	Without breathing沒有呼吸
Colour change of the cobalt chloride paper	Colour changes from blue to pink	No colour change

Discussion結論:

What can you see when you breathe on the mirror? Small droplets / moisture / a misty appearance

Conclusion:

Ø   Breathed air contains more water vapour than unbreathed air.

Laboratory safety

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F2 1st term SE 01 answers

Marks: =   / 22 =    %

1st Term SE 01 Submission date：_____________ Name：______________________ Class & no.：2 _________(     )

7.1 A    Composition of air I

i      Concept Checking

         Decide whether the following statements are true or false, and try to rewrite the true statements.                                                                                                                                            (10 marks)

1       Air contains oxygen, nitrogen, carbon dioxide and water vapour only.                     True / False

Air contains oxygen, nitrogen, carbon dioxide, water vapour, noble gases and other gases.

2        The composition of air is constant.                                                                        True / False

The composition of air is variable / not constant.

3        The percentage of water vapour in air is affected by the weather.                         True / False

_____________________________________________________________________________________

4        One difference between nitrogen and noble gases is that nitrogen is reactive while noble True / False

           gases are unreactive.                                                    

_____________________________________________________________________________________

5        The lights in commercial signs contain noble gases.                                                True / False

_____________________________________________________________________________________

i      Short Questions

1        *(a)  Why are noble gases also called inert gases (惰性氣體)? (1 mark)

Noble gases are unreactive. / Noble gases do not react with other chemicals easily.

           (b)     Name TWO noble gases and state ONE use for each of them. (4 marks)

Any TWO of the followings:

Helium. It is used to fill balloons.

Neon. It is used to fill neon light.

Argon. It is used to fill light bulbs.

2        (a)     What is the gas with the highest percentage in air? (1 mark)        Nitrogen

           (b)     State ONE use of this gas. (1 mark)

Nitrogen is used to fill food package so as to extend the shelf life of food. / Liquid nitrogen is used to store living cells./ Nitrogen is used to make fertilizers肥料.

i      Long Questions

1      The photo shows a light bulb. It is filled with gas X and there is a tungsten wire (鎢絲) inside. When electricity passes through the wire, the wire gives out light and heat.

         Vivian and Kenny are arguing what gas X is. Vivian thinks that it is

oxygen but Kenny thinks that it is a noble gas.

*(a)    Suggest why Kenny’s idea is more reasonable. (2 marks)

It is because noble gases are unreactive (1) and do not react with the tungsten wire (1), so that the wire can have a longer life.

           (b)     Name the noble gas that is used to fill light bulbs. (1 mark)           Argon.

           (c)     Name ONE other noble gas and state its use. (2 marks)

Neon; it is used to fill neon light. / Helium; it is used to fill balloons that float in air.

F2 1st term WS 00 answers

1st Term WS 00 Submission date：_____________ Name：______________________ Class & no.：2 _________(     )

Laboratory Safety Rules 實驗室安全守則

A      What should we do in a laboratory?

Complete the “Dos” part of the rules with the following words:

1.     instructions

2.     safety goggles

3.     accidents

4.     long hair

5.     fire escape route

6.     clean and tidy

7.     hands

B      What should we not do in a laboratory?

        Discuss with your partner and complete the “Don’ts” part of the rules.

        You may put down more than one word in each blank.

1.     is not in the laboratory

2.     eat and drink

3.     play

4.     solid wastes

5.     test tube

6.     experiment 

F2 1st Term WS 01 answers