science class 7 topic: solutions reinforcement worksheet · class 7 topic: solutions reinforcement...

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Science Class 7

Topic: Solutions Reinforcement Worksheet

Name:_____________________Sec:_______________________Date:_____________________

Q1 Choose the best answer. [5] 1. The pH of an acidic solution is

A. Less than 7 B. More than 7 C. 7 D. 0

2. The pH of a basic Solution is

A. Less than 7 B.More than 7 C. 7 D.0

3. Toothpaste helps to neutralize acid in the mouth as it’s slightly A. Acidic in nature B. Basic in nature C. Sweet in taste D. Sour in taste

4. It is the maximum amount of a solute that can be dissolved in a given amount of solvent

at a given temperature. A. Saturated B. Concentrated C. Solubility D. Polarity

5. What is the pH of pure water?

A. 5 B. 6 C. 7 D. 8

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6. As the temperature of a liquid solvent increases, the amount of solute that can dissolve in it;

A. decreases by one degree Celsius for every milliliter of solvent B. increases C. decreases D. remains constant

7. What is the substance being dissolved in a solution. A. Solute B. Solvent C. Substrate D. Insolvent

8. Which of the following is a strong acid? A. Citric Acid B. Acetic Acid C. Malic Acid D. Sulphuric Acid

9. Reaction between acid and base to form salt is called A. Combination reaction B. Neutralization reaction C. Decomposition reaction D. Addition reaction

10. All acids contain A. Oxygen B. Nitrogen C. Carbon D. Hydrogen

11. In case of indigestion, we use A. Antacids B. Antipyretic C. Antibiotic D. Alcohols

Q2. Fill in the blanks

1. Acids have _____________ taste. 2. Acids and alkalis are substances which dissolve in water to form ___________________

solutions. 3. Fizzy drinks contain ________________ acid.

http://www.helpteaching.com/questions/187975/as-the-temperature-of-a-liquid-solvent-increases-the-amount-

http://www.helpteaching.com/questions/187975/as-the-temperature-of-a-liquid-solvent-increases-the-amount-

http://www.helpteaching.com/questions/187987/anis-the-substance-being-dissolved-in-a-solution

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4. Blue litmus turns red in ________ solutions. 5. Our stomach contains strong acid called _________________ which helps to kill germs. 6. Another name for sodium hydroxide is __________________.

Q3. Match the following.

Column A Column B

a. Sulphuric acid i. Neutral salt

b. Sodium hydroxide ii. Weak base

c. Citric acid iii. Strong acid

d. Calcium hydroxide iv. Weak acid

e. Sodium chloride v. Strong base

Q4. Give reasons:

a, Toothpastes are made slightly alkaline.

______________________________________________________________________________

______________________________________________________________________________

b, Lime (calcium oxide) can be used to treat acidic soils.

______________________________________________________________________________

______________________________________________________________________________

Q5a. Name the factors affecting solubility.

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

b. Give at least 3 properties of Acids and Alkalis.

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

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c. Mention two uses of Neutralisation Reactions in daily lives.

__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________ d. Give word equation to show what happens when acid reacts with carbonates. ______________________________________________________________________________ e. Give word equation to show what happens when acid reacts with metals. ________________________________________________________________________

f. Explain why using acids can be dangerous. ______________________________________________________________________________

g) What is difference between concentrated and dilute acid? ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ h) Write the color change when sodium hydroxide (Na OH) is added to blue litmus paper and red litmus paper. ____________________________________________________________________________________________________________________________________________________________ i) What are indicators? Give two examples. __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Q6. Use the words in the box to complete the following paragraph.

Sulphuric acid is a ________ acid, but cows’ milk is a _________acid. ________acids and alkalis

tend to react more quickly than weak acids and alkalis. We use ________________

to tell us how strong acids and alkalis are. The_________ shows the range of strengths of acids

and alkalis. Alkalis have pH numbers _________ than acids.

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Q7. Use the graph below to answer the questions.

a) How much potassium nitrate will be dissolved in 10 cm3 of water? _____________ g

b) How much potassium nitrate will be

dissolved in 40 cm3 of water?

_____________ g

c) How much potassium nitrate will be


_____________ g

d) How much potassium nitrate will be


_____________ g

Q8. Read the following paragraph and find out the name of an acid, an alkali and a neutral

substance..

Peter got up one morning and had a wash with soap and water. For breakfast he had

orange juice and cereal with milk.

ACID: _________________ ALKALI: ______________ NEUTRAL: ___________

Q9. Identify the following terms :

a) Amount of solute dissolves in per 100 gm of water at a particular temperature. ___________

b) A solution which can’t dissolve any more solute at a particular temperature.______________

c) A process in which acids and alkalis react together to give salt and water.________________

d) Major quantity of a solution. ___________.

e) Group of chemicals which release Hydrogen ion in water. ___________.

Q10. Ainy’s family is at the beach during the summer. Ainy and her sister have a bucket containing seawater and sand.

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Read the following statements. Which are true and which are false? Tick one box for each statement.

Water is a solvent for salt._________

Sand sinks in water because water is more dense than sand. _________

When a solid dissolves in water, the solid is called a solute.__________ Q11.A deodorant has this warning sign on it.

a) What does this warning sign mean?

____________________________

b) A deodorant contains a solution of perfume and alcohol. What happens to the perfume when it is mixed with the alcohol? Tick the correct box.

Q12. Identify the name of acids and alkalis in the following substance.

a.

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________________________________________________________

b. _____________________________________________________

c. _____________________________________________________

d.

________________________________________________________

e. ________________________________________________________

Topic: Elements And Compounds

Q1.Choose the best answer. 1. Which of the following is an element? a) steam b) sugar c)dry ice d) sulphur 2. Which of the following is an element but NOT a metal? a) Oxygen b) copper c) aluminium d) salt 3. Which element can be found as charcoal, diamond or graphite? a) Carbon b) nitrogen c) zinc d) phosphorus

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4. Which metal is present in the liquid state at room temperature? a) Helium b) bromine c) mercury d) lithium 5. Which substance does not have fixed melting and boiling points? a) Water b) sugar c) ink d) sodium 6. Which of the following best supports the fact that air is a mixture? a) The oxygen in the air is easily removed during combustion. b) Air contains different elements. c) The water vapour is a chemical compound. d) The composition of the air remains almost constant throughout the world.

7. A compound contains a) Different kinds of atoms mixed together. b) The same kind of atom mixed together. c) Different kinds of atoms chemically combined together. d) The same kind of atom chemically combined together.

Q2. Fill in the blanks. a) Elements are classified into metals,__________ and __________ b) A _____________ is a substance which can not further divide by chemical reaction. c) The most found element in the air is_______________ d) In the periodic table, elements are arranged in columns called______________ Q3. Complete the given statements. (a)Rust is formed when iron objects are left out in the air. The iron reacts with the oxygen in the air, forming iron oxide. Rust be can turned back into iron, by mixing it with carbon and heating it. I think rust is _____________________ (an element / a mixture / a compound) because ______________________________________________________________________________ (b)Helium is a gas. There are tiny amounts of helium in the air. Helium does not burn, and will not react with any other chemicals. It cannot be split up by chemical reactions. It think helium is _____________________ (an element / a mixture / a compound) because ______________________________________________________________________________ Q4. Match the Columns.

A B

1) A Compound used in photosynthesis a) Mercury

2) An element present both in air and water b) Helium

3) A metal which is liquid at room temperature c) Carbon dioxide

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4) A metal used for making cooking pot d) Aluminum

5) A non metal used in air balloon e) oxygen

Q5. Are these statements true or false. Rewrite the false statement.

a) Elements are made of two or more different types of atoms. ___________________________________________________________________________ b) Mixtures have a definite composition. ___________________________________________________________________________ c) Compounds can be represented using a formula. ___________________________________________________________________________ d) A mixture of salt and water will boil at a higher temperature than pure water. ___________________________________________________________________________ e) Compounds can be decomposed on heating. ___________________________________________________________________________ f) The two most abundant elements in the Universe are Hydrogen & Helium. ___________________________________________________________________________ g) Chemical symbol for Copper is Co. ___________________________________________________________________________ h) Vertical columns in the periodic table are called periods. ___________________________________________________________________________ i) Elements in the same group in the periodic table share similar chemical properties. ___________________________________________________________________________ j) Compounds can only be broken into simpler substances by chemical reactions. ___________________________________________________________________________

Q6a. Complete the following table:

Compounds Elements they are made of Models of Compound

(i) Water

(ii) Carbon Dioxide

(iii) Ammonia

(iv) Iron Sulphide

(v) Sulphur Dioxide

b. Classify the following as Elements (Metals and non-metals) and compound. Carbondioxide, Iron, Sulphur, Helium, Nitrogen, Copper Sulphate, Copper, Oxygen, Aluminium, Carbon

Elements Compounds

Metals Non-metals

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c. Write two properties on the basis of which you differentiate metals from non-metals. __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ d. The formula of Aluminium sulphate is Al2(SO4)3

i) How many elements are present in the above formula. __________________________________________________________________________ ii) State the number of atoms of each element. __________________________________________________________________________ __________________________________________________________________________ e. When Magnesium burns in air a white ash is formed. i) Write a word equation for the reaction __________________________________________________________________________ __________________________________________________________________________ ii) Is this a physical or a chemical change? Give two reasons. __________________________________________________________________________ __________________________________________________________________________ Q7. When copper carbonate is heated copper oxide and a gas are formed. The gas when passed through lime water turns it milky as shown in the diagram below. i) Which gas is produced that turns lime water milky? __________________________________________________________________________ ii) Write a word equation for the above reaction. __________________________________________________________________________ Q8. An alloy is a mixture of elements.

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The table shows the mass of each element present in 100 g of five different alloys, bronze, solder, steel, stainless steel and brass. [4]

(a) Which alloy in the table above contains an element which is a non-metal? ______________________________________________________________________________ (b) Which two alloys in the table contain only two metals? ____________________________________ and ______________________________________ (c) Another alloy called nichrome contains only the elements chromium and nickel. 100 g of nichrome contains 20 g of chromium. How much nickel does it contain? _______________ g Q9. Identify each of the following picture as an element E or a compound C.

Q10. Below is the first 36 elements in the periodic table with their atomic numbers.

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(a) Give the symbol for one example of each of the following:

(i) a metal .............................(ii) an inert gas.......................

(iii)a non-metal in liquid state.............................

(b) Find chlorine in the table above. (i) What is the atomic number of Chlorine? .....................

(ii) What is the group number................................?

Q11. Different elements have different properties, some of which are shown below:

• Electrical insulator • Good thermal conductor

• Poor thermal conductor • High melting point

• Good electrical conductor • Shiny

• Ductile • Malleable

a) Gold is a metal. Give two properties of gold from the list above which make it a

good material to use as jewellery.

1 ...............................................................................................................................

2 ...............................................................................................................................

b) Krypton is a gas used inside a light bulb. Give two properties of krypton from the

list above which make it a good material to use.

1 ...............................................................................................................................

2 ...............................................................................................................................

c) Tungsten is used to make the filament inside a light bulb. Give two properties

from the list above which make it a good material to use.

(2)

1 ...............................................................................................................................

2 ...............................................................................................................................

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Q12. A science teacher showed her class three experiments, A, B and C. The experiments and the word equations for the reactions that took place are shown below. All the experiments were done in a fume cupboard.

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(a) From the substances in experiments A, B and C, above, give the name of: (i) three metallic elements; __________________________________________________ (ii) three non-metallic elements; ______________________________________________ (iii) two compounds. ________________________ and ________________________

(b) In experiment B, the iron filings weighed 2.0 g at the beginning of the experiment and the iron sulphide produced weighed 2.8 g. Explain this increase in mass. ____________________________________________________________________________________________________________________________________________________________ (c) Complete the word equation for the chemical reaction in experiment C.

copper + chlorine → ____________________________

Topic: Mixture Objective

Q.1 MCQs

1) A process to separate insoluble solid from liquid is

a) Evaporation b) Filtration

c) Condensation d) Crystallization

2) Gases from the air can be separated by

a) Filtration b) Distillation

c) Fractional distillation d) Chromatography

3) A process for the separation of colour pigments is

a) Distillation b) Evaporation

c) Chromatography d) Freezing

4) Petrol from the crude oil can be obtain through

a) Chromatography b) Fractional distillation

c) Solar distillation d) Simple distillation

5) Air is a type of

a) Gases b) Mixture

c) Compound d) Elements

6) Brass is an alloy of

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a) Copper and Zinc b) Copper and Tin

c) Iron and Copper d) Zinc and Silver

7) Diamond is an example of

a) Alloy b) Element

c) Mixtures d) Compound

8) Which of the following separation technique has been used to separate more than two

liquids with different boiling points?

a) Chromatography b) Distillation

c) Fractional Distillation d) Evaporation.

9) What is the residue obtained when sand and salts solution is filtered?

a) Sand b) Salt

c) Water d) No Residue

10) Which of the following are mixtures?

i) Air ii) Distilled water iii) Fizzy drink iv) Bronze

a) (i) and (ii) only b) (i) (ii) and (iii) only

c) (i) (ii) and (iv) only d) (i) (iii) and (iv) only

Q2. State whether True or False. Correct the false statement.

i) Chalk in water can be separated by filtration. [ ]

___________________________________________________________________________

ii) Police scientists use chromatography to solve crimes. [ ]

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___________________________________________________________________________

iii) Alcohol and water can be separated easily by fractional distillation. [ ]

___________________________________________________________________________

iv) Distillation involves boiling and condensation. [ ]

___________________________________________________________________________

v) Pure water boils at different temperatures in different parts of earth. [ ]

___________________________________________________________________________

Q3. Match the Column.

Column A Column B

Chromatography insoluble solid

Evaporation 100 °C

Condensation Blood

Distillation Liquid gases

Filtration Distilled water

Q4. Match the following gases in air with the percentage composition and write the answer in

column ‘C’.

Gases in Air (A) Percentage Composition (B) Column ‘C’

(i) Oxygen (a)78%

(ii) Carbon Dioxide (b)Variable

(iii) Nitrogen (c)21%

(iv) Rare Gases (d)0.03%

(v) Water Vapours (e) 1%

Q5. Name the method by which you will separate the following mixtures:

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(i) Iron Filings & Sulphur _________________________________________

(ii) Different Coloured Dyes _________________________________________

(iii) Ink & Water _________________________________________

(iv) Sand & Salt in Water _________________________________________

(v) Different Gases in Air _________________________________________

Q6a. State whether air & water are mixtures or compounds. Justify your answers giving two reasons for each. _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ b. Hydrogen is the lightest element. However, Helium is used in hot air balloons instead of Hydrogen. Explain. ______________________________________________________________________________________________________________________________________________________ Q7. Susie used chromatography to identify the coloured substances in the ink from a felt-tip pen. She used:

green ink

blue ink

purple ink

ink from her felt-tip pen.

She used water as the solvent.

Look at the diagram above.

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(a) (i) Which colours were present in the ink from the felt-tip pen.

______________________________________________________________________________

(ii) How many coloured substances were there in green ink? How can you tell?

______________________________________________________________________________

______________________________________________________________________________

(iii) Susie placed the spots of ink on a line on the chromatography paper as shown in the

diagram. To draw the line, Susie had to choose a felt-tip pen or a pencil.

Which one should she use?

______________________________________________________________________________

______________________________________________________________________________

(iv) Give the reason for your answer.

______________________________________________________________________________

_____________________________________________________________________________

(b) Susie used water as the solvent in this experiment.

When she repeated the experiment with a different set of pens, it did not work.

She then used ethanol instead of water.

Suggest why the experiment worked with ethanol but not with water.

______________________________________________________________________________

______________________________________________________________________________

Q8. Chris collected some sea water near a beach. The sea water had salt dissolved in it. It had sand mixed in it.

(a) Chris separated the sand from the salt water as shown below (i) What is this method of separation called? [1] Tick the correct box. Chromatography distillation

filtration magnetism

(ii) What is substance A? __________________________________________________ (iii) What is the part labelled B ? ____________________________________________

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(b) Chris poured some of the salt water from the flask into a dish. He put the dish on a balance and left it in a warm room for a week.

(i) Look at the two readings on the balance. Work out the decrease in mass: ________g (ii) After one week there was a white solid but no liquid in the dish. What had happened to the water in the dish? _________________________________________________________________ (iii) What was the white solid left in the dish? _________________________________________________________________

science class 7 topic: solutions reinforcement worksheet · class 7 topic: solutions reinforcement...

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