Worksheet on Elements, Compounds and Mixtures by parpar

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									Worksheet on Elements, Compounds and Mixtures

Name : ___________________________ (                  )          Date: 05042007

Class : _______________

Instruction: Answer all questions 1-9 below by filling the correct answer
in the given bracket.

1.    How many atoms are present in one molecule of sulphurous acid, H2SO3?
      A    3
      B    5
      C    6
      D    8                                                         (     )

2.    A mixture ________.
      A      has a fixed melting point.
      B      has a fixed boiling point.
      C      is made by a chemical reaction.
      D      can be separated by physical methods.                     (     )

3.    Which pair of substances are both mixtures?
      A air; sea water                    B diamond; vinegar
      C ethanol; lime water               D water; air
                                                                       (      )

4.    Which picture shows a compound made of two elements.




                                                                       (      )
5.    Which element conducts electricity at r.t.p.?
      A     Bromine.
      B     Nitrogen.
      C     Sulphur.
      D     Sodium.                                                    (     )

6.    Which one of the following sets contains only one metal?
      A     sodium          hydrogen       calcium
      B     iron            oxygen         sulphur
      C     copper          carbon         calcium
      D     sulphur         magnesium copper                           (     )

7.    Which one of the following is an element?
      A     Salt
      B     Water
      C     Air
      D     Chlorine                                                   (     )
8        The structural formula of glycerol is




                Which statement about glycerol is not true?

         A      Its molecular formula is C3H8O3.
         B      It contains three elements.
         C      One molecule contains a total of 14 atoms.
         D      Its molecular formula and empirical formula are different.   (   )

9.       Which diagrams correctly show the molecules in ammonia, nitrogen and
         hydrogen?

               ammonia               nitrogen             hydrogen
     A




     B




     C




     D




                                                                             (   )
Instruction: Questions 10-17 are structured questions. Fill your answers in the
blank spaces provided

10.    Choose your answers from the following list of substances.

       air            calcium        carbon dioxide
       chlorine       gold           hydrogen
       ice            nitrogen       sea water      sugar



(a)    Name four elements.




(b)    Name two substances that are mixtures.



(c)    Name two substances that are single compounds.



(d)    Name one solid compound that contains the element carbon.



11(a) The formula of one molecule of nitric acid is HNO3.

       (i)    Name the elements present in nitric acid.



       (ii)   What is the total number of atoms in one molecule of nitric acid?



12.    Fructose is a sugar used in food. The structural formula of one form of
       fructose is given below.
(i)     What are the elements present in fructose?



(ii)    What is the molecular formula of fructose?



(iii)   What is the empirical formula of fructose?



13.     A list of substances is given below.

        Air        Water Ethanol Steel         Chromium

        Graphite Petrol    Nylon     Protein

        Choose from the list one substance which

(i)     is an element.



(ii)    is a compound containing two elements only.



(iii)   is a compound containing nitrogen.



(iv)    is a mixture of compounds.



(v)     is a mixture of elements.




14(a) Substances can be classified as elements, compounds or mixtures. Put each
      of the following into one of these classes.
(i)     Air.


(ii)    Ammonia.



(iii)   Ethanol.
(iv)        Iodine.



(b)         Mixtures of metals (e.g. brass) are commonly called :



15. The properties of some metal oxides are given in the table. All the oxides are
    solid at room conditions.

        name of oxide                     formula of                    colour              effect of heating the oxide
                                             oxide
   copper(I) oxide                      Cu2O                          red               remains red

   lead(IV) oxide                       PbO2                          brown             oxygen produced;
                                                                                        solid turns yellow
   mercury(II) oxide                    HgO                           red               oxygen produced;
                                                                                        silvery liquid produced
   potassium peroxide                   K2O2                          white             remains white

   Zinc oxide                           ZnO                           white             solid turns yellow when hot and
                                                                                        becomes white again on cooling

 (a) Which of these oxides do not undergo a chemical reaction when heated?

       ............................................................................................................................. ..
                                                                                                                                  [2]

 (b) Suggest the identity of the silvery liquid formed from mercury(II) oxide.

        ..........................................................................................................................


16 (a) State three differences in the properties of elements that are metals and
       elements that are non-metals. Write your answer in the table below.

                                   Property                                          Metals                         Non-metals
              1
              2
              3

       (b) Anhydrite is a white rock with the formula CaSO4.

            Name the elements present in anhydrite and state whether each one is a
            metal or a non-metal.
      17. Fig. B shows some of the molecules in the air above an active volcano. For
          example, a water molecule has the formula H2O and is shown by         in the
          diagram. Write the formulas for the other molecules in the air above the
          volcano.

         .




                                                                       Fig B


18.      Use examples :a mixture of iron filings and sulphur, a compound iron(II)
         sulphide to illustrate the differences of properties between a mixture and a
         single compound.                                                             [4]

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