CLASS 7
REVISION WORKSHEET
RESPIRATION IN ORGANISMS

GENERAL SCIENCE

Class VII Assignment No: 10

Respiration in organisms

Q1 Name the following:-

a)  Inside the cells the breaking of food into water and carbon di oxide

b)  Cockroach breathe by these structures

c) I n fishes these are the breathing structures.

d)  The products formed as a result of glucose breakdown

e)  The type of respiration taking place in our muscles.

f) A large muscular sheet that forms the floor of the chest cavity Q2 Fill in the blanks:-

i) I f the food is broken with the help of oxygen , it is called as----------- --.

ii)  In earthworm exchange of gases takes place through----------

iii)  A cell is the smallest ------- and------------ unit.

iv)  during breathing ----------- and------------- take place alternately.

v)   Leaves have tiny pores called-------- --.

Q3 Why do all organisms respire?

Q4 What is the difference between aerobic and anaerobic respiration .Write equations for both.

Q5 Why are yeasts used to make wine and bear?

Q6 Why do we get muscle cramps after heavy exercise?

Q7 Draw and label a neat diagram of human respiratory system.

 Q8 What would happen if a potted plant is over watered

 Q9.How is respiration different from breathing?

Q 10 Aman is a talkative boy and keeps on talking even while eating food . His father dislikes this habit and asked him not to do so while eating . Can you explain the reason behind such an advice. What values are inculcated in Aman by his father .

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Revision worksheet force and pressure class -8

Force and Pressure Worksheet

Match the Column

Answer

True and false

a. Friction opposes the relative motion between two surfaces in contact.
b. A force can act on an object with or without being in contact with it.
c. Gases does not exert pressure on the walls of their container
d. The force exerted by a charged body on another charged or uncharged body
is known as gravitational force
e. magnetic force is a contact force
f.  force of gravity is an attractive force
g. Atmosphere pressure at high altitudes is less than the pressure at ground
h. People at plains suffer from nose bleeding.

Answer
a. True
b. True
c. False
d. false
e. False
f. true
g. true
h. False
 

Define

a. Muscular Force
b. Atmosphere pressure
c.  Contact Force
d.  Pressure
 

Conceptual Questions

a. Why shoulder bags are provided with broad straps and not thin straps
b. why the tools meant for cutting and piercing always have sharp edges
c. Two women are of the same weight. One wears sandals with pointed heels while the other wears sandals with flat soles. Which one would feel more comfortable while walking on a sandy beach? Give reasons for your answer.
d. Two persons are applying forces on two opposite sides of a moving cart. The cart still moves with the same speed in the same direction. What do you infer about the magnitudes and direction of the forces applied
e. Why do deep-sea divers have to wear special suits before going for diving at the depths?

Answers
c. The woman wearing sandals with flat soles will feel more comfortable while walking on the sandy beach. The flat soles have larger area compared to the sandals with pointed heels. Since the two women are of the same weight, they will apply same force on the ground. Therefore, the pressure exerted by the pointed heels will be more compared to that with sandals having flat soles. As a result, the pointed heel sandals will sink more in the sand than the flat sole sandals. Hence, walking with flat sole sandals will be more comfortable.
d. Both the forces are of equal magnitudes and applied in the opposite directions.

 Fill in the blanks

a. An example of a non-contact force is __________.
b. The pressure exerted by air around us is known as __________.
c. SI unit of force is __________.
d. Application of force can change the ______  or  __________ of an object.
e. Force exerted by our muscles is called __________ force.
f. Direction of force of friction is always __________ to the direction of motion.
g. Force per unit area is called ___________.
h. The force exerted by a charged body on another charged or uncharged body
is known as  ______________________
i.  Force has ________ as well as _________

Answer
a. Magnetic Force
b. Atmospheric pressure
c.  Newton
d.  Shape or state of motion
e. Muscular
f. opposite
g. Pressure
h. electrostatic force
i.  Magnitude and direction
 

Multiple Choice Questions

1. A ball rolling on the ground slows down and finally stops because
(a) force
(b) less force applied
(c) friction
(d) none of the above

2. The force involved in falling of an apple from a tree is known as?
(a) magnetic force
(b) electrostatic force
(c) contact force
(d) gravitational force

3. Which of the following is an example of a non-contact force?
(a) The force exerted by us to lift a bucket
(b) push a stationary car
(c) The force exerted by magnets
(d) Force due to friction

4. The below figure shows a container filled with water. Which of the following statements is correct about pressure of water?

(a) Pressure at A> Pressure at B> Pressure at C
(b) Pressure at A=Pressure at B=Pressure at C
(c) Pressure at A< Pressure at B>Pressure at C
(d) Pressure at A< Pressure at B < Pressure at C

5. Which one of the following forces is a contact force?
(a) force of gravity
 (b) magnetic force
(c) force of friction
 (d) electrostatic force

6.

A water tank has four taps fixed at points A, B, C, D as shown above
The water will flow out at the same pressure from taps at
 (a) B and C
(b) C and D
(c) A and B
(d) A and C

7. A brick is kept in two different ways on a table as shown below. The pressure exerted by the brick on the table will be

(a) maximum in position A
(b) maximum in position B
(c) equal in both cases

8. Opening the door is an example of which type of force?
(a) contact force
(b) spring force
(c) non-contact force
(d) magnetic force

9. Name the force used in removing iron scrap from a heap of mixed scrap.
(a)  Magnetic Force
(b) Electrostatic force
(c) Gravitational force
(d) Friction Force

10.  The pressure on an object _______ with the increase in altitude  from earth surface
(a) Increase
(b) decrease
(c) same
(d) None

Answer:
1. (c) friction
2. (d) gravitational force
3. (c) The force exerted by magnets
4. (d) Pressure at A< Pressure at B < Pressure at C
5. (c) force of friction
6. (a) B and C
7. (b) maximum in position B
8. (a) contact force
9. (a) Magnetic Force
10. (b) decrease
 

JUMBLED WORD

Answers
a. MAGNETIC
b. FORCE
c. CONTACT
d. PRESSURE
e.  GRAVITY
 

Crossword Puzzle
Across
2. The pressure exerted by air around us is known as ______ pressure
4. Push or pull on an object is known as _____
6. The force resulting due to the action of muscles is known as the  ________force
7. A _____ scientist of 17th century, invented a pump to extract air out of the vessel
9. Pressure exerted by water at the bottom of the container depends on the _______ of its column
Down
1. ______ force always acts opposite to the motion of the object
3. Force per unit area
5. Liquids exert ______ pressure at the same depth
8. gravity is an _____ force
Answer
1. Frictional
2. atmospheric
3. Pressure
4. force
5. equal
6. muscular
7. German
8. attractive
9. heigh

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CLASS 7 REVISION WORKSHEET
 ACIDS BASES AND SALTS

Class 7 Acids Bases and Salts

MULTIPLE CHOICE QUESTIONS (MCQS)

1. A neutralisation reaction between a strong acid and weak base forms :

(a) an acidic salt

(b) a basic salt

(c) a neutral salt

(d) a salt

2. Which of the following is a property of an acid?

(a) Sour taste

(b) Sweet taste

(c) Bitter taste

(d) Salty taste

3. Manure is added when the soil is too

(a) acidic

(b) basic

(c) neutral

(d) none of these

4. Which of the following is a strong acid?

(a) Nitric acid

(b) Citric acid

(c) Acetic acid

(d) Tartaric acid

5. The acid produced naturally in our stomach is :

(a) tartaric acid

(b) citric acid

(c) hydrochloric acid

(d) sulphuric acid

6. Which of the following is a strong base?

(a) Calcium hydroxide

(b) Sodium hydroxide

(c) Sodium carbonate

(d) Ammonium hydroxide

7. With which of the following ‘Milk of Magnesia’ be reacted so as to have neutralisation reaction?

(a) Baking soda

(b) Vinegar

(c) Ammonia solution

(d) Quicklime

 Ans.

1. (d) a salt
2. (a) Sour taste
3. (b) basic
4. (a) Nitric acid
5. (c) Hydrochloric acid
6. (b) Sodium hydroxide
7. (b) Vinegar

Fill in the blanks with suitable words

1. The reaction between an acid and a base is called———- ———–.

2.——————– is used to tell whether a material is acidic or basic.

3. Bases turn purple cabbage juice to—————-

4. Acid turns—– ——– litmus to ——- –—- —–

5. Acid + Base +————- —————-+ water.

6. Hydrochloric acid + Sodium hydroxide—––—- + water.

Ans.

1. neutralization reaction
2. Litmus paper
3. green
4. Blue, Red 
5. salt
6. salt

VERY SHORT ANSWER TYPE QUESTIONS.

1. Write the name of one natural indicator and one synthetic indicator.

Ans. Turmeric is naturally occurring indicator. Methyl orange is a synthetic indicator.

2. What is the name of the acid-base indicator which is extracted from lichens?

Ans. The solution is obtained from lichens. Litmus solution is used to detect the acidic and basic characteristic of a substance.

3. What colour do the following indicators turn when added to a base?

(a) Litmus solution

(b) China rose indicator

(c) Turmeric paper

(d) Phenolphthalein

Ans. (a) Litmus solution when litmus solution is added to a basic solution, it turns blue.

(b) China rose indicator solution turns from light pink to green.

(c) Turmeric paper bases turn the yellow turmeric paper to read.

(d) Phenolphthalein indicator gives pink colour in basic solution.

4. Name one indicator which turns red on adding a base?

Ans. Turmeric paper bases turn the yellow turmeric paper to read.

5. Name two weak acids and two strong bases.

Ans. Two strong acids are:

Acetic Acid

Citric  Acid

Two strong bases are:

Sodium hydroxide

Potassium hydroxide

6. Which chemical is injected by an ant, when it stings to one’s hand?

Ans. Formic acid is present in ant’s sting.

7. Which chemical is known as the king of acids?

Ans. Sulphuric acid is called the king of chemicals because it has a large number of applications.

8. Give one characteristic property of acids.

Ans. Acids have a sour taste.

9. Write one characteristic property of bases

Ans. Bases have a bitter taste.

Rena is trying to wash turmeric stain on her cloth with soap, she noticed the stain colour changed to red, explain why?

Q22. Give examples of some acids and bases.

Ans. Acids - Curd, lemon juice, vinegar, orange juice etc.

Base - baking soda, lime water etc.

Q23. What are indicators?

Ans. Solutions of substances that show different colour in acidic, basic and neutral solutions are called indicators.

Q24. What is the effect of the China rose indicator on acidic and basic solutions?

Ans. China rose indicator turns acidic solutions to dark pink (magenta) and basic solutions to green.

Q25. Ammonia is found in many household products, such as window cleaners. It turns red litmus blue. What is its nature?

Ans. Ammonia is basic in nature as it turns the red litmus blue.

Q26. Why a turmeric stain on my white shirt is turned to red when it is washed with soap.

Ans. A turmeric stain on my white shirt is turned to red when it is washed with soap because the soap solution is basic in nature.

Q27. How to prepare lime water?

Ans. To prepare limewater, dissolve some lime (chuna) in water in a bottle. Stir the solution and keep it for some time. Pour a little from the top. This is lime water.

Q28. Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.

Ans. The solution could be a base or neutral solution because blue litmus paper doesn’t change its colour in the neutral as well as in basic solution.

Q29. What do you mean by neutral solution? Give examples.

Ans. The solutions which do not change the colour of either red or blue litmus are known as neutral solutions. Examples- sugar solution, distilled water, salt etc.

Q30. Is the distilled water acidic/basic/neutral? How would you verify it?

Ans. Distilled water is neutral in nature. This can be verified by using red and blue litmus papers. Neither will show change in colour with distilled water. This proves that distilled water is neutral.

Q31. How does rain become acidic?

Ans. The rain becomes acidic because carbon dioxide, sulphur dioxide and nitrogen dioxide (which are released into the air as pollutants) dissolve in rain drops to form carbonic acid, sulphuric acid and nitric acid respectively.

Q32. Why factory waste is neutralised before disposing it into the water bodies?

Ans. The wastes of many factories contain acids. If they are allowed to flow into the water bodies, the acids will kill fish and other organisms. The factory wastes are, therefore, neutralised by adding basic substances.

Q33. Calamine solution is applied on the skin when an ant bites. Give reason.

Ans. When an ant bites, it injects the acidic liquid (formic acid) into the skin. The effect of the acid can be neutralised by rubbing moist baking soda (sodium hydrogen carbonate) or calamine solution, which contains zinc carbonate.

Q34. Name the source from which litmus solution is obtained. What is the use of this solution?

Ans. Litmus solution is extracted from lichens. It is most commonly used natural indicator. It has a mauve (purple) colour in distilled water. When added to an acidic solution, it turns red and when added to a basic solution, it turns blue.

Q35. Why we take an antacid tablet when we suffer from acidity?

Ans. Our stomach contains hydrochloric acid. It helps us to digest food. But too much of acid in the stomach causes indigestion. Sometimes indigestion is painful. To relieve indigestion, we take an antacid such as milk of magnesia, which contains magnesium hydroxide. It neutralises the effect of excessive acid.

Q36. Explain the process of neutralisation with the help of an example.

Ans. The reaction between an acid and a base is known as neutralisation. Salt and water are produced in this process with the evolution of heat.

Acid+Base → Salt+Water

(Heat is evolved)

The following reaction is an example:

 

a

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