Class 7 Science Olympiad preparation - Sample papers on Acids, Bases and Salts

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Science
Worksheets
Acids, Bases and Salts:
Set 01
Class 7
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07ABC | WS 01
Name: _______________________
Date: _______________
Do the correct matching of the acids and bases to where they are commonly
present / called.
1 ACETIC ACID - - Found in soap A
2 FORMIC ACID - - Found in Amla B
3 CITRIC ACID - -
Common name of zinc
carbonate
C
4 LACTIC ACID - - Found in lime water D
5 OXALIC ACID - - Calcium hydroxide in water E
6 ASCORBIC ACID - - Found in grapes F
7 TARTARIC ACID - -
Sodium hydroxide is also called
___
G
8 CALCIUM HYDROXIDE - - Found in ant's sting H
9 AMMONIUM HYDROXIDE - - Found in curd I
10 SODIUM HYDROXIDE - - Found in vinegar J
11 MAGNESIUM HYDROXIDE - - Found in window cleaner K
12 LIME WATER - - Common name of sulfuric acid L
13 CAUSTIC SODA - -
Common name of sodium
bicarbonate
M
14 OIL OF VITROIL - - Found in Spinach N
15 BAKING SODA - - Found in oranges O
16 CALAMINE SOLUTION - - Found in milk of magnesia P
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07ABC | WS 01
ANSWER SHEET
Do the correct matching of the acids and bases to where they are commonly
present.
1 J ACETIC ACID ⇢ Found in vinegar
2 H FORMIC ACID ⇢ Found in ant's sting
3 O CITRIC ACID ⇢ Found in oranges
4 I LACTIC ACID ⇢ Found in curd
5 N OXALIC ACID ⇢ Found in Spinach
6 B ASCORBIC ACID ⇢ Found in Amla
7 F TARTARIC ACID ⇢ Found in grapes
8 D CALCIUM HYDROXIDE ⇢ Found in lime water
9 K AMMONIUM HYDROXIDE ⇢ Found in window cleaner
10 A SODIUM HYDROXIDE ⇢ Found in soap
11 P MAGNESIUM HYDROXIDE ⇢ Found in milk of magnesia
12 E LIME WATER ⇢ Calcium hydroxide in water
13 G CAUSTIC SODA ⇢ Sodium hydroxide is also called ___
14 L OIL OF VITROIL ⇢ Common name of sulfuric acid
15 M BAKING SODA ⇢ Common name of sodium bicarbonate
16 C CALAMINE SOLUTION ⇢ Common name of zinc carbonate

07ABC | WS 02
Name: _______________________
Date: _______________
Try to solve the crossword on "Acids, Bases and Salts: in 10 minutes.
Across
1. Acid found in vinegar
3. Acid found in oranges
4. Acid found in curd
6. Acid found in Amla
10. ___ hydroxide is found in soap
15. Common name of sodium bicarbonate
16. Common name of zinc carbonate
Down
2. Acid found in ant's sting
5. Acid found in Spinach
7. Acid found in grapes
8. ___ hydroxide is found in lime water
9. ___ hydroxide is found in window cleaner
11. ___ hydroxide is found in milk of magnesia
12. Calcium hydroxide in water
13. Sodium hydroxide is also called ___
14. Common name of sulfuric acid
6 5 13
1 14 9
11 12
4 7 8
15
2
10
3
16

07ABC | WS 02
ANSWER SHEET
A
6
S C O
5
R B I C A C
13
I D
X A
A
1
C E T I C U O
14
A
9
M
11
L
12
L S I M
L
4
A C T I C A C I D T
7
T L M C
8
G M C B
15
A K I N G S O D A
N E R C O N L
E A T F I C
S W F
2
C A S U I
I A S
10
O D I U M R O V M U
U T R D I D I M
M E M C A T
R I R
C
3
I T R I C A C I D O
C I
C
16
A L A M I N E S O L U T I O N L
D

07ABC | WS 03
Name: _______________________
Date: _______________
Try to solve the crossword on "Acids, Bases and Salts" in 10 minutes.
Across
2. Color of methyl orange in acidic medium
5. Natural indicator
6. Used to test whether a substance is acidic
or basic
7. Most commonly used indicator
8. Litmus is a natural dye extracted from ___
9. Rain containing acids
10. Reaction between an acid and a base
13. Olfactory indicator
Down
1. Color of methyl orange in basic medium
3. Color of phenolphthalein in acidic medium
4. Synthetic acid base indicator
11. Acid present in body cells which control
every feature of our body
12. Color of litmus in distilled water
14. Obtained by neutralization reaction
15. A natural indicator which gives green color
in basic solutions
1
7 4 5 3
2 11
6 15
13
12 14
9
8
10

07ABC | WS 03
ANSWER SHEET
Y
1
L
7
I T M U S P
4
A P E R T
5
U R M E R I C
3
H L O
R
2
E D D
11
L L
N I
6
N D I C
15
A T O R O
O A H W R
L O
13
N I O N L
P N E
H M
12
A S
14
S
T A
9
C I D R A I N S
H U R L
A V O T
L
8
I C H E N S S S
E E
N
10
E U T R A L I Z A T I O N
N

07ABC | WS 04
Name: _______________________
Date: _______________
Do the correct matching.
1 YELLOW - - Rain containing acids A
2 RED - - Obtained by neutralization reaction B
3 COLORLESS - - Color of methyl orange in basic medium C
4 PHENOLPHTHALEIN - - Color of litmus in distilled water D
5 TURMERIC - - Reaction between an acid and a base E
6 INDICATOR - - Olfactory indicator F
7 LITMUS PAPER - -
Color of phenolphthalein in acidic
medium
G
8 LICHENS - - Natural indicator H
9 ACID RAIN - -
Acid present in body cells which control
every feature of our body
I
10 NEUTRALIZATION - - Synthetic acid base indicator J
11 DNA - -
A natural indicator which gives green
color in basic solutions
K
12 MAUVE - -
Used to test whether a substance is
acidic or basic
L
13 ONION - - Most commonly used indicator M
14 SALTS - -
Litmus is a natural dye extracted from
___
N
15 CHINA ROSE - -
Color of methyl orange in acidic
medium
O

07ABC | WS 04
ANSWER SHEET
Do the correct matching.
1 C YELLOW ⇢ Color of methyl orange in basic medium
2 O RED ⇢ Color of methyl orange in acidic medium
3 G COLORLESS ⇢ Color of phenolphthalein in acidic medium
4 J PHENOLPHTHALEIN ⇢ Synthetic acid base indicator
5 H TURMERIC ⇢ Natural indicator
6 L INDICATOR ⇢ Used to test whether a substance is acidic or basic
7 M LITMUS PAPER ⇢ Most commonly used indicator
8 N LICHENS ⇢ Litmus is a natural dye extracted from ___
9 A ACID RAIN ⇢ Rain containing acids
10 E NEUTRALIZATION ⇢ Reaction between an acid and a base
11 I DNA ⇢
Acid present in body cells which control every feature of our
body
12 D MAUVE ⇢ Color of litmus in distilled water
13 F ONION ⇢ Olfactory indicator
14 B SALTS ⇢ Obtained by neutralization reaction
15 K CHINA ROSE ⇢ A natural indicator which gives green color in basic solutions

07ABC | WS 05
Name: _______________________
Date: _______________
Decode the cryptogram to reveal interesting facts.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
81 80 71 67 79
T G
85 66 89 86 69 65 85 66 67 66 74 65 89 70 86 80 70 75 89 68
C T
85 70 86 88 81 69 65 69 82 90 83 66 89 86 67 66 89
T C
68 69 65 82 67 70 69 86 70 68 84 74 68 70 81 74 86 87
M C
90 89 71 74 70 86 81 69 65 69 82 90 65 89 68 68 83 66 89 86
T C C .
68 69 65 82 67 70 69 86 70 68 74 81 70 87 70 81
C C C
83 66 89 86 74 81 70 87 70 81 74 86 87 84 74 68 70 81
T M X
68 69 65 82 67 70 69 86 68 74 90 89 71 70 79 89 87 70 86
T T T , T
68 82 70 67 74 84 65 89 72 82 74 86 67 70 67 73 67 66 89 73

T T C C
87 89 68 67 90 69 73 67 66 89 74 81 70 87 70 81 74 86 87
C T T
84 74 68 70 81 86 74 67 82 90 89 69 77 67 66 89
T .
68 69 65 82 67 70 69 86

ANSWER SHEE
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
74 84 81 87 89 77 80 66 70 78 88 65 71 86 69 85 72 90 68 67 82 75 83 79 73 76
P H E N O L P H T H A L E I N G I V E S
85 66 89 86 69 65 85 66 67 66 74 65 89 70 86 80 70 75 89 68
P I N K C O L O U R W H E N T H E
85 70 86 88 81 69 65 69 82 90 83 66 89 86 67 66 89
S O L U T I O N I S B A S I C A N D
68 69 65 82 67 70 69 86 70 68 84 74 68 70 81 74 86 87
R E M A I N C O L O U R L E S S W H E N
90 89 71 74 70 86 81 69 65 69 82 90 65 89 68 68 83 66 89 86
S O L U T I O N I S A C I D I C .
68 69 65 82 67 70 69 86 70 68 74 81 70 87 70 81
W H E N A C I D I C A N D B A S I C
83 66 89 86 74 81 70 87 70 81 74 86 87 84 74 68 70 81
S O L U T I O N S A R E M I X E D I N
68 69 65 82 67 70 69 86 68 74 90 89 71 70 79 89 87 70 86
S U I T A B L E Q U A N T I T Y , T H E Y
68 82 70 67 74 84 65 89 72 82 74 86 67 70 67 73 67 66 89 73

D E S T R O Y T H E A C I D I C A N D
87 89 68 67 90 69 73 67 66 89 74 81 70 87 70 81 74 86 87
B A S I C N A T U R E O F T H E
84 74 68 70 81 86 74 67 82 90 89 69 77 67 66 89
S O L U T I O N .
68 69 65 82 67 70 69 86

07ABC | WS 06
Name: _______________________
Date: _______________
Fill in the blanks with the words given in the box to complete the article on
"ACIDS, BASES AND SALTS".
turmeric laboratory strips purple blue
damages BASIC indicator red fungi
Blue algae lemon red detects
naturally two droplets bitter colour
not red ACIDIC sour pink
vinegar symbiotic green vehicles Red
blue phenolphthalein harmful soda
Substances can be divided into three types – Acid, Base and Salt.
ACID: Taste of acid is sour. There are many substances that contain acid and so taste sour. For
example – __________, curd, pickles, orange juice, ______________, etc.
Substances that taste sour are called acidic. The chemical nature of such substance is known as
____________.
The word acid comes from Latin 'ACERE' which means ________.
BASE: Taste of base is ____________. Substances that contain base taste bitter. For example;
soap or soap solution, baking soda, washing ________, etc.
The chemical nature of substances that contain base is known as __________.
INDICATOR: A substance which ______________ the acidic or basic nature of another substance
by change in ____________ is called acid-base __________________. It is not advisable to taste
any substance in laboratory because it can be harmful. Hence, acid-base indicators are used to
check if a given substance is acid or base.
Types of Indicator:
Indicators can be divided into two types.
Natural Indicator: Indicators that are obtained from __________________ occurring substance are
called NATURAL INDICATORS. Example: litmus, ________________, China rose, etc.
Synthetic Indicator: Indicators that are made in ____________________ are called SYNTHETIC
INDICATORS. Example: ______________________________, methyl orange, etc.

NATURAL INDICATORS:
Litmus: Litmus is extracted from Lichens. Lichen is a composite organism. Lichens consist of
__________ and __________ living in __________________ relationship.
Litmus is a ____________ coloured liquid in distilled water. Litmus comes in the form of
____________ of ______ colours. One is called ________ litmus paper and another is called ______
litmus paper. Litmus liquid and litmus paper are used to detect the acidic or basic nature of a
substance.
Colour of litmus paper in acid: ________ litmus paper turns into ______ when dipped in acidic
solution.
Colour of litmus paper in base: ______ litmus paper turns into ________ when dipped in basic
solution.
Turmeric: Turmeric is also used as natural indicator. Turmeric is of yellow colour. Turmeric paper
turns into ______ when it is dipped into basic solution. Turmeric paper does ______ change its
colour with acid.
China Rose: China rose is another natural indicator. China rose solution gives dark ________
(magenta) colour with acid and __________ colour with base.
Acid Rain: Carbon dioxide, sulphur dioxide and nitrogen dioxide which are released from
________________ and chimneys mix with ________________ of rain and turn the rain water acidic.
When this acidic rain water falls over earth, it is known as acid rain. Acid rain ______________ the
buildings and is ______________ for plants and animals.

07ABC | WS 06
ANSWER SHEET
Substances can be divided into three types – Acid, Base and Salt.
ACID: Taste of acid is sour. There are many substances that contain acid and so
taste sour. For example – lemon , curd, pickles, orange juice, vinegar , etc.
Substances that taste sour are called acidic. The chemical nature of such substance
is known as ACIDIC .
The word acid comes from Latin 'ACERE' which means sour .
BASE: Taste of base is bitter . Substances that contain base taste bitter. For
example; soap or soap solution, baking soda, washing soda , etc.
The chemical nature of substances that contain base is known as BASIC .
INDICATOR: A substance which detects the acidic or basic nature of another
substance by change in colour is called acid-base indicator . It is not advisable to
taste any substance in laboratory because it can be harmful. Hence, acid-base
indicators are used to check if a given substance is acid or base.
Types of Indicator:
Indicators can be divided into two types.
Natural Indicator: Indicators that are obtained from naturally occurring substance
are called NATURAL INDICATORS. Example: litmus, turmeric , China rose, etc.
Synthetic Indicator: Indicators that are made in laboratory are called SYNTHETIC
INDICATORS. Example: phenolphthalein , methyl orange, etc.
NATURAL INDICATORS:
Litmus: Litmus is extracted from Lichens. Lichen is a composite organism. Lichens
consist of fungi and algae living in symbiotic relationship.
Litmus is a purple coloured liquid in distilled water. Litmus comes in the form of
strips of two colours. One is called blue litmus paper and another is called
red litmus paper. Litmus liquid and litmus paper are used to detect the acidic or
basic nature of a substance.
Colour of litmus paper in acid: Blue litmus paper turns into red when dipped in
acidic solution.
Colour of litmus paper in base: Red litmus paper turns into blue when dipped in
basic solution.
Turmeric: Turmeric is also used as natural indicator. Turmeric is of yellow colour.

Turmeric paper turns into red when it is dipped into basic solution. Turmeric paper
does not change its colour with acid.
China Rose: China rose is another natural indicator. China rose solution gives dark
pink (magenta) colour with acid and green colour with base.
Acid Rain: Carbon dioxide, sulphur dioxide and nitrogen dioxide which are released
from vehicles and chimneys mix with droplets of rain and turn the rain water
acidic. When this acidic rain water falls over earth, it is known as acid rain. Acid rain
damages the buildings and is harmful for plants and animals.

07ABC | WS 07
Name: _______________________
Date: _______________
Tick (✔) true or false for each statement.
1. Distilled water is basic
1. True
2. False
2. Sodium hydroxide and hydrochloric
acid neutralize each other to form
salt and water.
1. True
2. False
3. Nitric acid turns red litmus blue
1. True
2. False
4. Bases are the chemical opposites
of acids
1. True
2. False
5. Sodium hydroxide turns blue litmus
red
1. True
2. False
6. A solution of sodium chloride salt
in water does not change the color
of any litmus paper
1. True
2. False
7. Tooth decay is caused due to the
presence of an acid.
1. True
2. False
8. All acids have hydrogen as a
compulsory constituent element.
1. True
2. False
9. An alkali is a water soluble acid.
1. True
2. False
10. Baking soda is a mild base.
1. True
2. False

07ABC | WS 07
ANSWER SHEET
1. Distilled water is basic
1. True
2. False
2. Sodium hydroxide and hydrochloric
acid neutralize each other to form
salt and water.
1. True
2. False
3. Nitric acid turns red litmus blue
1. True
2. False
4. Bases are the chemical opposites
of acids
1. True
2. False
5. Sodium hydroxide turns blue litmus
red
1. True
2. False
6. A solution of sodium chloride salt
in water does not change the color
of any litmus paper
1. True
2. False
7. Tooth decay is caused due to the
presence of an acid.
1. True
2. False
8. All acids have hydrogen as a
compulsory constituent element.
1. True
2. False
9. An alkali is a water soluble acid.
1. True
2. False
10. Baking soda is a mild base.
1. True
2. False

07ABC | WS 08
Name: _______________________
Date: _______________
1. Bases neutralize acids to form salt
and water
1. True
2. False
2. A base is an oxide or hydroxide of
a metal which forms salt and water
only with an acid.
1. True
2. False
3. The pH of pure water is less than
7.
1. True
2. False
4. All bases dissolve in water
1. True
2. False
5. Orange juice turns blue litmus red.
1. True
2. False
6. Milk of magnesia contains
magnesium hydroxide.
1. True
2. False
7. Alum acts as antacid
1. True
2. False
8. Sting of an ant contains vinegar
1. True
2. False
9. Sugar is a neutral substance.
1. True
2. False
10. Acids are sour in taste.
1. True
2. False

07ABC | WS 08
ANSWER SHEET
1. Bases neutralize acids to form salt
and water
1. True
2. False
2. A base is an oxide or hydroxide of
a metal which forms salt and water
only with an acid.
1. True
2. False
3. The pH of pure water is less than
7.
1. True
2. False
4. All bases dissolve in water
1. True
2. False
5. Orange juice turns blue litmus red.
1. True
2. False
6. Milk of magnesia contains
magnesium hydroxide.
1. True
2. False
7. Alum acts as antacid
1. True
2. False
8. Sting of an ant contains vinegar
1. True
2. False
9. Sugar is a neutral substance.
1. True
2. False
10. Acids are sour in taste.
1. True
2. False

07ABC | WS 09
Name: _______________________
Date: _______________
Search for 15 words you would often find in the chapter "Acids, Bases and Salts".
The words are placed in all directions (including reverse) and tightly interweaved.
P H E N O L P H T H A L E I N C
T F I C Y B F K I Y S N D F L M
N O I T A Z I L A R T U E N I V
T U Y U L T Q T P V L Z R F B H
R X E G X B U X D N A D Z R B I
E S L C O L O R L E S S S M S P
P S L Y K Y M B M D B X H J I J
A Q O E B M A U V E B D F N S P
P J W R H P E H N R R O D S K O
S L Z N A V E U E O N I O N H Y
U I L A U N P Z O K C V C E Y G
M G O T A C I D R A I N H H O K
T G G M J Z S H T D X T E C I G
I F Y S C P Z O C T Z O D I X O
L P N S O V R A D Y M T G L V J
S W V Y D H I L H J Z E K W G N

07ABC | WS 09
ANSWER SHEET
P H E N O L P H T H A L E I N C
T F I C Y B F K I Y S N D F L M
N O I T A Z I L A R T U E N I V
T U Y U L T Q T P V L Z R F B H
R X E G X B U X D N A D Z R B I
E S L C O L O R L E S S S M S P
P S L Y K Y M B M D B X H J I J
A Q O E B M A U V E B D F N S P
P J W R H P E H N R R O D S K O
S L Z N A V E U E O N I O N H Y
U I L A U N P Z O K C V C E Y G
M G O T A C I D R A I N H H O K
T G G M J Z S H T D X T E C I G
I F Y S C P Z O C T Z O D I X O
L P N S O V R A D Y M T G L V J
S W V Y D H I L H J Z E K W G N
YELLOW ↓ RED ↑ COLORLESS →
PHENOLPHTHALEIN
→
TURMERIC
↘
INDICATOR
↙
LITMUS PAPER
↑
LICHENS
↑
ACID RAIN → NEUTRALIZATION ← DNA → MAUVE →
ONION → SALTS ↑
CHINA ROSE
↖
15 words in Wordsearch: 5 vertical, 7 horizontal, 3 diagonal. (7 reversed.)

07ABC | WS 10
Name: ________________________
Date: _______________
1. Neutralization reaction is
accompanied by evolution of
heat.
1. True
2. False
2. Neutralization reaction is a
reaction between an acid and a
base to form salt and water.
1. True
2. False
3. Turmeric is a natural indicator.
1. True
2. False
4. Turmeric acquires orange colour
in alkaline solution.
1. True
2. False
5. Onions cannot be used as
indicators.
1. True
2. False
6. Litmus is a natural dye and is
extracted from papyrus.
1. True
2. False
7. Limewater turns milky when we
breathe through it.
1. True
2. False
8. Red litmus turns blue in a solution
containing vitamin C.
1. True
2. False
9. Vinegar is acidic in nature.
1. True
2. False
10. Alkali is a base which is not
soluble in water.
1. True
2. False

07ABC | WS 10
ANSWER SHEET
1. Neutralization reaction is
accompanied by evolution of
heat.
1. True
2. False
2. Neutralization reaction is a
reaction between an acid and a
base to form salt and water.
1. True
2. False
3. Turmeric is a natural indicator.
1. True
2. False
4. Turmeric acquires orange colour
in alkaline solution.
1. True
2. False
5. Onions cannot be used as
indicators.
1. True
2. False
6. Litmus is a natural dye and is
extracted from papyrus.
1. True
2. False
7. Limewater turns milky when we
breathe through it.
1. True
2. False
8. Red litmus turns blue in a solution
containing vitamin C.
1. True
2. False
9. Vinegar is acidic in nature.
1. True
2. False
10. Alkali is a base which is not
soluble in water.
1. True
2. False

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Class 7 Science Olympiad preparation - Sample papers on Acids, Bases and Salts

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Class 7 Science Olympiad preparation - Sample papers on Acids, Bases and Salts