Class 10 Science Acid base and Salts Practice worksheet
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a. Match the column
b. Fill in the blanks
c. True and False
e. Short Answer Questions
f. Long answer questions(5 Marks)
Common Salt :NaCl Backing soda: NaHCO3 Caustic soda:NaOH Washing Soda:Na2CO3
Fill in the blanks
Question 3
(a) Chemical formula for bleaching powder is ______.
(b) Acids ______ _______ bases to form ________ and water.
(c) The term pH was coined by _______ .
(d) An acidic solution contains _____ _______ ions .
(e)________ ________ is used in softening water.
(f) ______ medicine used to treat indigestion
(g) Calcium Sulphate hemihydrate is popularly known as _____ ___ _____.
(i) ________ are present in aerated drinks Solution
(a)CaOCl2
(b)React, with. salt
(d) H+
(e)Washing Soda
(f)antacid
(g) Plaster of Paris
(i) CO2
True and False
Question 4 True and False statement
(a) Vinegar contains acetic acid
(b) Formic acid is a weak acid
(c) Acids gives H+ ion in water
(d) Baking soda is used for Softening of hard water
(e) pH of a solution can vary from 0-14.
(f) Heat is evolved during ionization.
(g) NaCl is a base
(h) Acids turns blue litmus solution to red Solution
Question 5
Name four gases that can be prepared in the laboratory using dilute H2SO4. Show how they can be prepared? Solution
The four gases are:
(1) H2 gas : An active metal (above Pb) and dilute H2SO4 gives H2 gas
(2) CO2 gas :Any carbonate salt and dilute H2SO4 gives CO2 gas
(3) SO2 gas :Any sulphite salt and dilute H2SO4 gives SO2 gas
(4) H2S gas : Any sulphide salt and dilute H2SO4 gives H2S gas.
Question 6
A milkman adds a very small amount of baking soda to fresh milk.
(a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
(b) Why does this milk take a long time to set as curd? Solution
So that it does not set as curd easily
Since Milk is alkaline in nature,acid produced are neutralized by the base ,so it takes longer time to set into curd
Question 7
(a) What is lime water?
(b) How plaster of paris is formed?
(c) What is the pH of our stomach
(d) Name a strong base and a weak base.
(e) Name a hydrated salt
(f) What is a universal indicator? What is its advantage? Solution
(a) Limewater is the common name for a diluted solution of calcium hydroxide
(c)Range 1-3
(d)Strong Base is NaOH and Weak Base is NH4OH
(e) A hydrated salt is copper sulphate crystals (CuSO4.5H2O).
(f) A universal indicator is a mixed indicator of organic chemicals which not only shows whether the given solution is acidic or basic, but also shows the approximate pH values by giving a wide particular colour for a specific value of pH.
Long Answer type
Question 8
(a) List in tabular form two differences between an acid and a base based on their chemical properties?
(b) State the meaning of neutralization reaction ?. Give two examples to illustrate your answer.
Question 9
A student dropped few pieces of marbles in dilute hydrochloric acid, contained in a test tube. The evolved gas was then passed through lime water. What change would be observed in lime water? What will happen if excess of gas is passed through lime water? Write balanced chemical equations for all the changes observed. Solution
Marble is nothing but calcium carbonate
CaCO3 + HCl -> CaCl2 + H20 + CO2
When CO2 is passed through lime water,The first reaction produces CaCO3 which is insoluble in water and hence the solution turns milky.
Ca(OH)2 [lime water] + CO2 -- CaCO3 + H2O
If furthermore CO2 is passed,the CaCO3 reacts with the CO2 to form Ca(HCO3)2 which is soluble in water and hence the solution becomes colourless.
CaCO3 + CO2 + H2O -- Ca(HCO3)2
Question 10
What is observed when carbon dioxide gas is passed through lime water.
(a) for a short duration?
(b) for long duration?
Also write the chemical equations for the reactions involved. Solution
When CO2 is passed through lime water,The first reaction produces CaCO3 which is insoluble in water and hence the solution turns milky.
Ca(OH)2 [lime water] + CO2 -- CaCO3 + H2O
If furthermore CO2 is passed,the CaCO3 reacts with the CO2 to form Ca(HCO3)2 which is soluble in water and hence the solution becomes colourless.
CaCO3 + CO2 + H2O -- Ca(HCO3)2
Question 11
State reasons for the following statements:
(a) Tap water conducts electricity, whereas distilled water does not.
(b) Dry hydrogen chloride gas does not turn blue litmus red, whereas hydrochloric acid does.
(c) During summer season, a milkman usually adds a very small amount of baking soda to fresh milk.
(d) For dilution of an acid, acid is added into water and not water into acid.
(e) Ammonia is a base but does not contain a hydroxyl group. Solution
(a) Tap water contains ions which conduct electricity, distilled water does not contain ions.
(b)Dry HCl does not form ions but HCl gives H+ and Cl–.
(c) Baking soda does not allow milk to change to lactic acid which makes milk sour.
(d) Adding water to acid is highly exothermic. Therefore water is added to acid very slowly with cooling.
(e)Ammonia when dissolved in water it forms ammonium hydroxide.
Ammonium hydroxide readily ionizes to form ammonium ions (NH4+) and hydroxide ions
(OH-). Thus the solution ammonia is considered as a base
Question 12
(a) In a tabular form write the colours of the following indicators in presence of acid and base:
Litmus solution, phenolphthalein solution, methyl orange solution
(b) Classify the following given solution A and B in acidic and basic, giving reason.
SOLUTION A: [H+] < [OH-]
SOLUTION B: [H+] > [OH-] Solution
(a)
(b)
(i) Solution A is having more hydroxide ion showing that it is basic.
(ii) Solution B is having more H+ showing that its acidic.
Question 13
(a) A metal compound ‘X’ reacts with dil. H2SO4 to produce effervescence. The gas evolved extinguishes a burning candle. If one of the compound formed is calcium sulphate then what is ‘X’ and the gas evolved? Also, write a balanced chemical equation for the reaction which occurred.
(b)
(i) Name one antacid. How does it help to relieve indigestion in stomach?
(ii) A farmer treats the soil with quick lime or calcium carbonate. What is the nature of soil? Why does the farmer treat the soil with quick lime? Solution
(a) X is calcium carbonate and gas evolved is CO2
(b)
(i) NaHCO3 is antacid. It neutralizes excess of acid formed in the stomach.
(ii) The soil is acidic in nature. The farmer wants to make it neutral by adding quicklime which is good for crops.
Question 14
State what happens when sodium hydroxide solution reacts with dilute hydrochloric acid. What is this reaction called?
Question 15
Write the chemical name and formula of common salt. List two main sources of common salt in nature. Write any three uses of common salt. How is it connected to our struggle for freedom?
Question 16
An aqueous solution of sodium chloride is neutral but an aqueous solution of sodium is basic.
Question 17
What is chlor-alkali process? Write the chemical reaction taking place in the form of a balanced chemical equation. Name the gases liberated at the cathode and at the anode respectively. Solution
When concentrated solution of sodium chloride is electrolysed it forms Chlorine gas, Sodium hydroxide and Hydrogengas. It is called chlor-alkali process because of the products formed- Chlor for chlorine gas and alkali for Sodium hydroxide. Chlorine is formed at anode and Hydrogen is formed at the cathode and Na(OH)2 is formed near the cathode.
The main products formed are: Chlorine and Sodium Hydroxide
Question 18
(a) What is baking soda? How is it known chemically?
(b) What is the nature of this salt?
(c) Write one application of it.
(d)Write chemical names and formulae of Plaster of Paris and gypsum.
Question 19
How do metal carbonates and metal hydrogen carbonates react with acids?
Question 20
A metal carbonate X on reacting with an acid gives a gas which when passed through a solution Y gives the carbonate back. On the other hand, a gas G that is obtained at anode during electrolysis of brine is passed on dry Y, it gives a compound Z, used for disinfecting drinking water. Identify X, Y, G and Z. Solution
X is Calcium carbonate (CaCO3).
CaCO3 + Acid = Metal Salt + Water + CO2
If we take the acid as HCl then the reaction would be:
CaCO3 + 2HCl -------> CaCl2 + CO2 + H2O
Y is Lime water Ca(OH)2 or slaked lime.When this CO2 gas is passed through Lime water , the lime water turns milky due to the formation of Calcium Carbonate and thus it is formed again.
Ca(OH)2 + CO2 ---------> CaCO3 + H2O
The gas evolved at anode during electrolysis of brine is chlorine (G) When chlorine gas is passed through dry Ca(OH)2 (Y) produces bleaching powder (Z) used for disinfecting drinking water.
2Ca(OH)2 + 2Cl2 ------> Ca(OCl)2 + CaCl2 + 2H2O
Summary
This Class 10 Science Acid base and Salts Practice worksheet with answers is prepared keeping in mind the latest syllabus of CBSE . This has been designed in a way to improve the academic performance of the students. If you find mistakes , please do provide the feedback on the mail.
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