LESSON 5 KEY

3.  Listening - Dictation

                  Earth´s crust

   Element                            %

                Sea Water

  Element                            %

            Whole Earth

   Element                            %

   oxygen 49.9

  Oxygen 91

  Iron 40-50

  silicon 25.8

     Hydrogen 5.7

  Oxygen 22-28

  Aluminium 7.5

  Chlorine 2

  Silicon 11-15

  Iron 4.7

  Sodium 1

  Magnesium 9

  Calcium 3.4

  Magnesium 0.1

  Nickel 3-6

  Sodium 2.6

  Sulfar 0.08

  Calcium 1-2

  Potassium 2.4

  Calcium 0.04

  Aluminium 1-2

  Magnesium 2.0

  Potassium 0.04


  Hydrogen 0.9

  Bromine 0.01


  Titanium 0.5

  Carbon 0.003




                                    Article: THE WONDER METALS

5.  iron, aluminium, magnesium




6.


1.      What is the chemical substance called fool’s gold? Iron pyrite

2.      What are the most common alloys formed with iron? Steel, stainless steel, and cast iron

3.      What is the advantage of aluminium over iron? It does not corrode so easily and is lighter

4.      Where does magnesium occur? In sea water

5.      Which elements react violently in water? Sodium, potassium, calcium



7. Listen to these statements about three metals: iron, aluminium and lead. Complete the chart.^2



                                 IRON

                                          ALUMINIUM

                                                             LEAD

Density

                       high

                                     low

                                                   High

Does it corrode?

                      easily

                                     no

                                                   no

Is it easy to extract?

                      yes

                                     no

                                                   yes


8. a-2, b-2, c-1, d-2, e-1, f-1, g-1, h-2


9. chromium – platinum- copper-gold-zinc-sodium-mercury


Grammar revision

a)      2. It takes longer to  travel by train than by car.

3.      I ran more kilometres than Dave.

4.      Joe did worse in the exam than Chris


b)      ugly-uglier-the ugliest

destructive- more destructive- the most destructive

unpleasant- more unpleasant- the most unpleasant

far- farther/further- the farthest/furthest


c)      2. I need something much bigger.

3.      I’m afraid the problem is much more complicated than it seems.

4.      You looked depressed this morning but you look a bit happier now.

5.      It was far more interesting than I expected.


d)      2. My salary isn’t as high as yours.

3.      You don’t know as much about cars as I do.

4.      It isn’t as cold today as it was yesterday.


e)      2. Your hair is the same colour as mine.

3.      I arrived at the same time as you.

4.      My birthday is the same day as yours.


f)        2. I know more than him.

3.      Most people work as hard as me.

4.      Nobody was more surprised than us.

5.      I’m a better player than her.