Grade 7 Chemistry All Class Assessment and Revision of Examination

 

Grade 7 Chemistry All Class Assessment and Revision of Examination 

1.     ---------------------- is a natural rock

a)    Element

b)    Ore

c)     Atom

2.     The metal in ores are chemically bonded to other ------------------

d)    Element

e)    Ore

f)      Atom

3.     The least reactive ones are at the -----------------

g)    tope

h)    middle

i)       bottom

4.     Ores are rocks from which it is economical to extract metals that they contain.

A)    True

B)    False

5.     The least reactive ones are at the top

A)    True

B)    False


 

 

j)       Most metal are found naturally in --------------------------- called ores.

A.    Element

B.    rocks

C.    Atom

k)       Gold is very expensive because it is ----------------------to find.

A.    difficult

B.    easy

C.    both A & B

l)       ---------------- is a process of heating an ore to a high temperature in the presence of air.

A.    Blasting

B.    Roasting

C.    Melting

m)  The metal above copper in the Reactivity Series is lead.

C)   True

D)   False

n)    Carbon is a metal.

C)   True

D)   False

 

 

1.     Haematite is -------------------

A.    Iron

B.    Cock

C.    Limestone

2.     A cheap form of carbon is

D.    Iron

E.    Coke

F.    Limestone

3.     -------------------------- breaks down into calcium oxide

G.   Iron

H.    Cock

I.       Limestone

 

4.     The molten slag floats on top of the iron.

A.    True

B.    False

5.     The slag is tapped off, cooled and used for making roads.

A.    True

B.    False

6.     This carbon reacts with more hot coke to make carbon monoxide liquid.

A.  True

B.  False

 

7.     Steel is made from ------------ ore

J.     Iron

K.    Cock

L.     Limestone

8.     The iron from the blast furnace is -------------------.

M.   pure

N.    impure

O.   soft

9.     -------------------------- is a form of iron(III) oxide .

P.    Iron

Q.   Cock

R.    Rust

 

10. Rust forms on the surface of iron.

C.    True

D.    False

11. Both air (oxygen) and water are needed for iron to rust.

C.    True

D.    False

12. Air and water will make iron safe.

C.  True

D.  False

 

1.    The metals are located on the ---------- side of the Periodic Table.

S.    left

T.    right

U.    both

2.    The metals are located on the left side of the Periodic Table are----------------- reactive.

A.    most

B.    less

C.    both

3.    Galvanizing is a method of -------------------- prevention.

A.    Iron

B.    Cock

C.    Rust

 

13. Rust forms on the surface of iron.

E.    True

F.    False

14. Highly reactive metals are expensive to extract.

E.    True

F.    False

15. Rust resistant alloys. 

E.  True

F.   False

 

 

1. A molecules that is made up of only two atoms is called ……………. molecules.

1.     Diatomic                   b. mono atomic               c. triatomic

2. Fluorine gas exist in ………….. State.

1.     Solid                          b. gas                                 c. liquid

3. Chlorine element belongs to group …………?

a. 1                                 b. 6                                     c. 7

 

1.     The molecules that consist of three atoms are called …….. Molecules?

1.     Mono atomic              b.. Diatomic                c. triatomic

2. Halogens do not conduct electricity?

1.     True                               b. false                         c. none

3. Noble gases are called mono atomic molecules because they consist of only …………. Atom?

a. One                                b. two                        c. three

 

1.     Aqueous solution of Chlorine acts as a ……….?

1.     Catalyst                     b. Enzyme                  c. bleach

1.     Halogens react with metals to form …………..?

1.     Acid                            b. Base                       c. Salt

3. Halogen react with H2 gas to form …………?

1.     Acid                            b. Base                       c. Salt

4. 2Na   +  Cl2 à  …………..    ?

a.   2NaCl                         b.  NaCl                     c. NaCl2

 

1.     Reaction in which more reactive element displaces the less reactive element from its compound are called…….?

1.     Displacement reaction       b. Active reaction        c. Atom

1.     Density of halogens increases ………. the group?

1.     Down                              b. Up                        c. none

3. Reactivity of halogens ……………. down the group?

a. Increases                       b. Decreases           c. Stable

 

1. Noble gases are unreactive (stable) because their outermost shells are …………. full of electrons?

1.     Partially                         b. completely                c.  Ionic

2. Group-VIII elements are called ………….. gases?

1.     Noble                             b. halogen                   c. alkali

 

3. …………. is used in Killing bacteria in swimming pools?

a. Flourine                          b. Chlorine                   c. Bromine

 

1.     ……………  is used in air ships(weather balloon).

1.     Helium                        b. Argon                      c. Bromine

2. ……………  is used in red signs (e.g. traffic signals).

1.     Chlorine                      b. Neon                       c. Iodine

3. …………..  is radioactive and is used to treat  cancer.

1.     Radon                          b. Argon                    c. Uranium

4. ………….  is used in laser to operate eye.

a. Polonium                      b. Iron                         c. Krypton

 

1. Periodic table are arranged in order of

1.     Atomic mass                         b. Atomic number                c.  Ions

2. Atoms of elements in the some group in the Periodic Table

    have the some number of -------------------- in their outer shell.

    a. Proton                             b. Neutron                   c. electron

 

3. When an atom loss or gain electron it become

a. ion                          b. compound                   c. molecule

 

4. The inner shells of electrons ---------------- the outer electrons from the pull of the nucleus.

     a. save                          b. shield                   c. react

 

Class Assessment

1.     Loss of electron by an atom is called ………….?

Oxidation                    b.  Reduction         c. Redox  reaction

2. In ………… state of electrolytes, ions are not free to move?

Liquid                            b. Solid                 c. Gas

3. Compounds that do not conduct electricity even in molten or solution form are called ……………….. ?

a. Electrolytes   b. Metal Electrode    c. non-Electrolytes

    4.  Lead, Pb2+, gains -------- electrons forming lead atoms.

    a)  2              b) 4                       c)  6

5. Metals donate electrons forming positive ions 

For example:      

       a)            Na+,    K+,      Ca2+,     Al3+

       b)           Cl-,    Br-,     I-,     O2-

       c)            Both a & b

 

1.  Lead as a metal will be collected on cathode. T

2.  Bromine being a non-metal will be collected on anode. T

    3.  Aluminum is highly reactive metal. T

   4.  Oxygen reacts with hot carbon anodes making carbon dioxide gas & burns away. T

   5.  Aluminum is extracted mainly from its ore called Bauxite (Al2O3). T

  6.  Aluminum oxide is dissolved in a chemical Cryolite (Na3AlF4). T

7.  Ions are free to move in solution of the compounds. T

8.  Hydrogen being a non – metal, is deposited on cathode. T

    9.  Hydrogen is a monoatomic molecule. F 

10.  Calcium is more reactive & stable than hydrogen. T 

11.  Active electrode is a metal that is used in electrochemical cells. T

12.  Mostly we use Iron electrodes. F

    13.  Copper is a best conductor of electricity. T

    14.  During the electrolysis, impurities fall down in cell. T 

15.  Smelting copper ores is the main source to provide  copper. T

16.  Rock-eating bacteria are Bio-leaching. T 

17.  About 10% copper is extracted by leaching method. F

    18.  Addition of acid costs money. T

19.  Iron oxide is reduced to iron by loss of iron. F

20.  Carbon monoxide is oxidised to carbon dioxide by gain of oxygen. T 

21.  Oxidation is loss of electrons. T 

22.  Reduction is gain of electrons. T  

23.  Copper as a metal will be collected on cathode. T 

24.  Chlorine being a non-metal will be collected on anode. T 

25.  Half – equation shows the external chemistry of a chemical reaction. F 

26.  Cl is a diatomic molecule. T 

27.  Electrodes are rods (plates) made up of graphite or metals. T 

28.  The negative electrode is called Anode. F 

29.  The positive electrode is called Cathode. F 

30.  Negative ions are called Anions. T  

31.  Positive ions are called Cations. T   

32.   Decomposition of a compound by passing electricity through is called Electrolysis. T 

33.   A compound that does not conduct electricity in solid form but it only conducts in molten or solution form is called Electrolyte. T 

34.   Electrolytic cell is a device that uses electrical energy to start a chemical reaction. T






 

 

 

 

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