CBSE Class 7 Science Acids Bases and Salts Assignment

I. Fill in the blanks:-

1. An acid is ____________ by a base .

2. Phenolphthalein is an __________ indicator.

II. Choose the correct option:-

1. A Soap Solution is –

a) Basic b) Acidic c) Alkaline d) Neutral

2. CO₂ + H₂O →

a) Sulphuric acid b)Nitric acid c) Carbonic acid d) None

III Name the following:-

1. Soluble bases.

2. A Chemical used as a food preservative.

3. Chemical name of Chile Salt Petre.

IV Define the following:-

1. Acid Rain 2. Neutralisation Reaction 3. Acid-Base Indicator

V Give Reasons:-

1. Non Metal Oxides are called Acidic .

2. Metal Oxides are Basic

3. Sour things are not kept in metal pots

4. Metal Oxides such as MgO are used for making refractory bricks.

VI Complete the Equations:-

1. ________ + 2O₂ → CO₂ + H₂O

2. 3NO₂ + H₂O → NO + _______ .

3. 2NaOH + H₂SO₄ → _________ + 2H₂O

4. CaCO₃ → ________ + CO₂

VII Answer in 20 words :-

1 Name three mineral acids and give their formulae?

2 What is acid and base?

VIII Answer in 40 words:-

1. What are general properties of bases?

2. What are general properties of acids?

3. Name an acidic gas which is discharged into the atmosphere on the burning of fuels like coal

& natural gas. How is this gas formed?

IX Answer in 100 words:-

1. Describe an activity to show the effect of acid on carbonates and hydrogen carbonates?

2. What is acid rain? How is it formed? Mention three bad effects of acid rain .

X Write one use of the following:-

1. Sulphuric acid.

2. Citric acid

3. Sodium Carbonate

4. Potassium Nitrate

5. Calcium phosphate

Q.1 Fill in the blanks.

i) An acid testes s_______________

ii) A base tastes b__ tt____________

iii) LItmus, a natural indicator is extracted from Li_____________.

iv) An indicator used in a neutralisation reaction is phe___ph_____lein.

v) Sugar is a n....u............l substance.

Q.2 Match the following.

         Column I                      Column II

a) An antacid                    i) Formic acid

b) An Ant                         ii) Milk of magnesia

c) China Rose                iii) Turns red litmus blue.

d) An acid                       iv) A natural indicator

e) A base                        v) Turns blue litmus red.

Answer : a. b. c. d. e.

Q.3 Bring a soil sample of your area, find out weather it is acidic, basic or neutral with the help of red or blue litmus solution /paper. Write this observation in the space given below.

Q.4 According to their nature give proper place to each substance given below. 

Curd, Common Salt, Vinegar, Soap, Sugar, Lime water, Lemon Juice, Window Cleaner.

1. Acidic Nature .................

2. Basic Nature .................

3. Neutral Substances .................

Q.5 Complete the following table