Grade 8 Examination Portion coverage 3rd Term exam 21-22 and Answer Key

Chapter 22 Water (complete chapter) 
All Class Assessment
 
1.    ----------------- on Earth Without depends on water.
A.  Car
B. Life
C. Mobile
2.    The formula of ------------------- is H₂O.
A.   carbon monoxide
B. methane
C.         water
3.    The hydrogen and -------------- atoms are joined by covalent bonds in water molecule.
A. oxygen
B.  carbon
C. nitrogen 
4.    ------------------------ is the changing of a liquid into a gas.
A. Evaporation 
B.  Condensation
C. Precipitation
5.    ------------------------ is the changing of a gas into a liquid.
A.  Evaporation 
B. Condensation
C. Precipitation
6.    A --------------------------- is an area from which water is drained.
A.  Evaporation 
B. watershed
C. Precipitation
7.    Water freezes at 0 °C and boils at 100°C.
A. True
B.  False
8.    Water is a gas at most temperatures on Earth.
A.  True
B. False
9.    Precipitation is any form of water that falls from the atmosphere and reaches the ground, such as rain, sleet, snow, or hail.
A. True
B.  False
10.                   Precipitation that flows across the land's surface and is absorbed will flow into rivers, lakes, and streams as runoff.
A.  True
B. False
11.                   Groundwater is stored in tiny holes, or pores, in soil and rocks.
A. True
B.  False
12.                   New salts enter the sea, other salts are being deposited
        on the ------------------ floor as solids.
A.  Car
B. ocean
C. Mobile
13.                   Oceans also contain dissolved --------------------.
A.  oxygen
B.  carbon
C. gases
14.                   Salts have entered the oceans following their weathering from rocks on land.
A. True
B.  False
15.                   The dissolved salts are carried to the sea by rivers.
A. True
B.  False
16.                   The oceans play an important part in the carbon cycle as reservoirs for carbon dioxide.
A. True
B.  False
17.                   About two-thirds of the mass of your body is made up of -----------
A.  carbon monoxide
B.  methane
C. water
18.                   Iron(III) hydroxide causes vegetables to turn ------------------.
A. brown
B.  blue
C. pink  
19.                   Dirty water is a -------------------.
A.  Evaporation  
B. sol
C. Precipitation
20.                   The acidity of the water is controlled using lime-----------------.
A. slurry
B.  Condensation
C. Precipitation
21.                   Calcium hydroxide is alkaline so it raises the pH of the water.
A. True
B.  False
22.                   Water is filtered through layers of stones and gravel to make sure all solids are removed.
A.  True
B. False
23.                   Remove any excess chlorine by treating the water with sulfur dioxide.
A. True
B.  False
24.                   Chlorine is added to kill bacteria in the water.
A. True
B.  False
25.                   The chlorine is reduced to chloride ions.
A. True
B.  False
26.                   Calcium in the -------------------- is good for children.
A.  Car
B. water
C. Mobile
27.                   Scum forms in a reaction which wastes -----------.
A.  carbon monoxide
B.  methane
C. soap
28.                   Calcium (or magnesium) compounds dissolved in water make it---------.
A. hard
B.  blue
C. pink  
29.                   Calcium sulfate is slightly soluble in -------------------.
A. water  
B.  sol
C. alcohol
30.                   calcium carbonate is not soluble in -----------------.
A. water  
B.  sol
C. alcohol
31.                   Bits of white scum will float around in the water when you use soap.
C. True
D. False
32.                   Water is filtered through layers of stones and gravel to make sure all solids are removed.
C. True
D. False
33.                   The scale formed can even block up pipes completely.
A. True
B.  False
34.                   Rainwater is the purest water.
A.  True
B. False
35.                    A coating of scale (limescale) inside copper or lead pipes stops poisonous salts dissolving into our water.
A. True
B.  False
36.                   The calcium or magnesium in the water is present as charged particles called --------------.
A.  atom
B. ion
C. molecule 
37.                   Calcium ions react with ions from soap (sodium stearate) to form -------.
A.  methane
B.  soap
C. scum
38.                   Temporarily hard water can be softened by---------------------.
A. boiling
B.  filtering
C. Cooling   
39.                   When you add -------------- to hard water, the calcium ions are removed.
A.  washing soda  
B.  sol
C. alcohol
40.                   calcium carbonate is not soluble in -----------------.
A. water  
B.  sol
C. alcohol
41.                   Most modern washing powders have their own water softeners.
A. True
B.  False
42.                   The column is filled with a resin which holds plenty of carbon ions.
A.  True
B. False
43.                   A solid forms when two solutions are mixed, it is called a precipitation reaction.
A. True
B.  False
44.                   The calcium ions get stuck on the resin.
A. True
B.  False
45.                    A coating of scale (limescale) inside copper or lead pipes stops poisonous salts dissolving into our water.
A. True
B.  False
46.                   The --------------- of a substance tells us how many grams of it will dissolve in 100g of water at a certain temperature.
A. solubility
B.  ion
C. salts 
47.                   Special desalination -------------- can take most of the dissolved salts out of sea water.
A.  methane
B.  soap
C. plants
48.                   Water is -------------------, then cooled and condensed to separate it from dissolved solids.
A.  evaporated
B.  filtered
C. Cooled
49.                   the solubility of sodium chloride is 36g per ---------- of water at 25°C.
A. 100g
B.  88g
C. 78g
50.                   100 cm3 of ------------- has a mass of 100g.
A.  water  
B.  sol
C. alcohol
51.                   --------------------------- is used in Middle East countries.
A.  Evaporation 
B. Desalination
C. Precipitation
52.                   Only a certain amount of solute can dissolve in a particular volume of solvent at any given temperature.
A. True
B.  False
53.                   A saturated solution is a solution in which no more solute will dissolve at a given temperature.
A.  True
B. False
54.                   The process used in some desalination plants is based on distillation.
A. True
B.  False
55.                   The calcium ions get stuck on the resin.
A. True
B.  False
56.                   Solubility curves enable you to read the solubility at temperatures you didn't investigate.
A. True
B.  False
57.                   The --------------- of a substance tells us how many grams of it will dissolve in 100g of water at a certain temperature.
A. solubility
B.  ion
C. salts 
58.                   Special desalination -------------- can take most of the dissolved salts out of sea water.
A.  methane
B.  soap
C. plants
59.                   Water is -------------------, then cooled and condensed to separate it from dissolved solids.
A. evaporated
B.  filtered
C. Cooled
60.                   the solubility of sodium chloride is 36g per ---------- of water at 25°C.
A. 100g
B.  88g
C. 78g
61.                   100 cm3 of ------------- has a mass of 100g.
A. water  
B.  sol
C. alcohol
62.                   --------------------------- is used in Middle East countries.
A.  Evaporation 
B. Desalination
C. Precipitation
63.                   Only a certain amount of solute can dissolve in a particular volume of solvent at any given temperature.
A. True
B.  False
64.                   A saturated solution is a solution in which no more solute will dissolve at a given temperature.
A.  True
B. False
65.                   The process used in some desalination plants is based on distillation.
A. True
B.  False
66.                   The calcium ions get stuck on the resin.
A. True
B.  False
67.                   Solubility curves enable you to read the solubility at temperatures you didn't investigate.
A. True
B.  False