MCQs For NCERT Class 10 Science Chapter 2 Acids, Bases And Salts

Please refer to the MCQ Questions for Class 10 Science Chapter 2 Acids Bases And Salts with Answers. The following Acids, Bases and Salts Class 10 Science MCQ Questions have been designed based on the current academic year syllabus and examination guidelines for Class 10. Our faculty has designed MCQ Questions for Class 10 Science with Answers for all chapters as per your NCERT Class 10 Science book.

Acids, Bases and Salts Class 10 MCQ Questions with Answers

Please see below Acids, Bases and Salts Class 10 Science MCQ Questions, solve the questions and compare your answers with the solutions provided below.

Question. Which of the following is a strong acid ?   
(a) H₂CO₃
(b) CH₃COOH
(c) HCl
(d) HCOOH

Question. Choose an example of inorganic acid (mineral acid) from the following      
(a) Oxalic acid
(b) Acetic acid
(c) Nitric acid
(d) Formic acid

Question. Which of the following is not basic in nature ?   
(a) KOH
(b) Ca(OH)₂
(c) K₂SO₄
(d) ZnO

Question. Mark the correct statement.     
(a) Both bases and alkalies are soluble in water.
(b) Alkalies are soluble in water but all bases are not.
(c) C₂H₅OH is a base because it has OH group.
(d) Bases are soluble in water but alkalies are not.

Question. Acidity of ammonium hydroxide is 
(a) 1
(b) 2
(c) 4
(d) 3

Question. Which one of the following will turn red litmus blue?   
(a) Vinegar
(b) Baking soda solution
(c) Lemon juice
(d) Soft drinks

Question. A blue litmus paper was first dipped in dil. HCl and then in dil. NaOH solution. It was observed that the colour of the litmus paper 
(a) changed to red
(b) changed first to red and then to blue
(c) changed blue to colourless
(d) remained blue in both the solutions

Question. The reaction of metal with acid results in the formation of   
(a) only hydrogen gas
(b) only salt
(c) both salt and hydrogen gas
(d) None of these

Question. When zinc reacts with sodium hydroxide, the products formed are 
(a) zinc hydroxide and sodium
(b) sodium zincate and water
(c) sodium zincate and hydrogen gas
(d) sodium zincate and oxygen

Question. Acetic acid is a weak acid because   
(a) its aqueous solution is acidic
(b) it is highly ionized
(c) it is weakly ionized
(d) it contains –COOH group

Question. The incorrect statement about acids is   
(a) they give H+ ion in water
(b) they are sour in taste
(c) they turn blue litmus red
(d) they give pink colour with phenolphthalein

Question. Which of the following metals can displace hydrogen from the aqueous solution of sodium hydroxide ?   
(a) Mg
(b) Cu
(c) Al
(d) Ag

Question. Acids react with metals to liberate _________gas 
(a) Carbon dioxide
(b) Carbon monoxide
(c) Hydrogen
(d) Water

Question. Acids react with metal carbonates to liberate ______ gas
(a) Carbon dioxide
(b) Carbon monoxide
(c) Hydrogen
(d) Water

Question. Lime water turns milky when carbon dioxide is passed due to the formation of ______. 
(a) CaCO₃
(b) CaO
(c) CO₂
(d) CaSO₄

Question. Acids react with bases to form salt and water. This reaction is known as: 
(a) Combination
(b) Decomposition
(c) Neutralisation
(d) reduction

Question. When CO₂ is passed through lime water, it turns milky. The milkiness is due to formation of 
(a) CaCO₃
(b) Ca(OH)₂
(c) H₂O
(d) CO₂

Question. When an oxide of a non-metal reacts with water which of the following is formed ?   
(a) Acid
(b) Base
(c) Salt
(d) None of these

Question. Which of the following is ‘quicklime’ ?     
(a) CaO
(b) Ca(OH)₂
(c) CaCO₃
(d) CaCl₂.6H₂O

Question. Which of the following does not give H+ ions in aqueous solution? 
(a) H₂CO₃
(b) C₂H5OH
(c) CH₃COOH
(d) H₃PO₄

Question. Which one of the following is a strong electrolyte?     
(a) Carbon disulphide
(b) Ammonium hydroxide
(c) Sodium chloride
(d) Water

Question. A solution turns blue litmus red. The pH of the solution is probably      
(a) 8
(b) 10
(c) 12
(d) 6

Question. When bitten by an ant, the sting causes irritation due to the presence of     
(a) a base in the sting
(b) formic acid in the sting
(c) poisonous chemicals
(d) Both (1) and (2)

Question. pH + pOH equals 
(a) zero
(b) fourteen
(c) a negative number
(d) infinity

Question. Antacids contain   
(a) weak base
(b) weak acid
(c) strong base
(d) strong acid

Question. Which of the following compounds is neutral to litmus ? 
(a) NaNO₃
(b) CuSO₄.5H₂O
(c) NaHCO3
(d) Ca(OH)₂

Question. Chemical formula of baking soda is 
(a) MgSO₄
(b) Na₂CO₃
(c) NaHCO₃
(d) MgCO₃

Question. The difference of water molecules in gypsum and Plaster of Paris is 
(a) 5/2
(b) 2
(c) 1/2
(d 3/2

Question. You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. Which of them will turn red litmus to blue.   
(a) Acid
(b) Base
(c) Water
(d) All of the above

Question. The milkiness (on passing excess carbondioxide gas through lime water) disappears due to the formation of: 
(a) Calcium carbonate CaCO₃
(b) Calcium hydrogen carbonate CaHCO₃
(c) Calcium oxide CaO
(d) Calcium Nitrate Ca(NO₃)₂

Question. The milkiness (on passing excess carbondioxide gas through lime water) disappears due to the formation of: 
(a) Calcium carbonate CaCO₃
(b) Calcium hydrogen carbonate CaHCO₃
(c) Calcium oxide CaO
(d) Calcium Nitrate Ca(NO₃)₂

Question. When a bee stings, immediately a paste of lime is put on the sting. Why? 
(a) Bee sting is made of a base
(b) Bee sting contains an acid called formic acid. It gets neutralised with CaO .
(c) Bee sting is acidic due to hydrochloric acid and this is neutralised
(d) All of the above

Question. Which of the following statements is correct about an aqueous solution of an acid and a base? 
(i) Higher the pH, stronger the acid
(ii) Higher the pH, weaker the acid
(iii) Higher the pH, stronger the base
(iv) Lower the pH, weaker the base
(a) (i) and (iii)
(b) (ii) and (iii)
(c) (ii) and (iv)
(d) (ii) and (iv)

Question. An aqueous solution ‘A’ turns phenol-phthalein solution pink. On addition of an aqueous solution ‘B’ to ‘A’ and ‘B’.
(a) A is strongly basic and B is a weak base.
(b) A is strongly acidic and B is a weak acid.
(c) A has pH greater than 7 and B has pH less than 7.
(d) A has pH less than 7 and B has pH greater than 7.

Question. A student requires hard water for an experiment in his laboratory which is not available in the neighbouring area. In the laboratory there are some salts, which when dissolved in distilled water can convert it into hard water. Select from the following groups of salts, a group, each salt of which when dissolved in distilled water will make it hard.
(a) Sodium chloride, potassium chloride
(b) Sodium sulphate, potassium sulphate
(c) Sodium sulphate, calcium sulphate
(d) Calcium sulphate, calcium chloride

Question. Which of the following is used for dissolution of gold ?
(a) Hydrochloric acid
(b) Sulphuric acid
(c) Nitric acid
(d) Aqua regia

Question. Which of the following gives the correct increasing order of acidic strength ?
(a) Water < Acetic acid < Hydrochloric acid
(b) Water < Hydrochloric acid < Acetic acid
(c) Acetic acid < Water < Hydrochloric acid
(d) Hydrochloric acid < Water < Acetic acid

Question. A student took four test tubes P, Q, R and S and filled about 8 ml. of distilled water in each. After that he dissolved an equal amount of Na₂SO₄ in P, K₂SO₄ in Q, CaSO₄ in R and MgSO₄ in S. On adding an equal amount of soap solution and shaking each test tube well, a good amount of lather will be obtained in the test tubes :
(a) P and Q
(b) P and R
(c) P, Q and S
(d) Q, R and S

Question. Which of the following is not a mineral acid ?
(a) Hydrochloric acid
(b) Citric acid
(c) Sulphuric acid
(d) Nitric acid

Question. When you add a few drops of acetic acid to a test-tube containing sodium bicarbonate powder, which one of the following is your observation ?
(a) No reaction takes place.
(b) A colourless gas with pungent smell is released with brisk effervescence.
(c) A brown coloured gas is released with brisk effervescence.
(d) Formation of bubbles of a colourless and odourless gas.

Question. Sodium hydrogen carbonate when added to acetic acid evolves a gas. Which of the following statements are true about the gas evolved ?
(i) It turns lime water milky.
(ii) It extinguishes a burning splinter.
(iii)It dissolves in a solution of sodium hydroxide.
(iv)It has a pungent odour.
(a) (i) and (ii)
(b) (i), (ii) and (iii)
(c) (ii), (iii) and (iv)
(d) (i) and (iv)

Question. Which of the following phenomena occur, when a small amount of acid is added to water ?
(i) Ionisation, (ii) Neutralisation,
(iii)Dilution, (iv) Salt formation.
(a) (i) and (ii) (b) (i) and (iii)
(c) (ii) and (iii) (d) (ii) and (iv)

Question. If a few drops of a concentrated acid accidentally spills over the hand of a student, what should be done ?
(a) Wash the hand with saline solution.
(b) Wash the hand immediately with plenty of water and apply a paste of sodium hydrogen carbonate.
(c) After washing with plenty of water apply solution of sodium hydroxide on the hand.
(d) Neutralise the acid with a strong alkali.

Question. If you take some distilled water in a test-tube, add an equal amount of acetic acid to it, shake the test-tube well and leave it undisturbed on the test-tube stand, then after about 5 minutes, what would you observe ?
(a) There is a layer of water over the layer of acetic acid.
(b) A precipitate is settling at the bottom of the testtube.
(c) Bubbles of colourless gas are coming out of the test-tube.
(d) There is a clear, colourless transparent solution in the test-tube.

Question. You have four test tubes, A, B, C and D containing sodium carbonate, sodium chloride, lime water and blue litmus solutions respectively. Out of these the material of which test tube/test tubes would be suitable for the correct test of acetic/ethanoic acid ?
(a) Only A
(b) A and B
(c) B and C
(d) A and D

Question. One of the constituents of baking powder is sodium hydrogen carbonate, the other constituent is :
(a) Hydrochloric acid
(b) Tartaric acid
(c) Acetic acid
(d) Sulphuric acid

Question. For demonstrating the preparation of soap in the laboratory which of the following combination of an oil and a base would be most suitable ?
(a) Mustard oil and calcium hydroxide
(b) Castor oil and calcium hydroxide
(c) Turpentine oil and sodium hydroxide
(d) Mustard oil and sodium hydroxide.

Question. Which one of the following can be used as an acid– base indicator by a visually impaired student?
(a) Litmus
(b) Turmeric
(c) Vanilla essence
(d) Petunia leaves

Question. Which among the following is not a base ?
(a) NaOH
(b) KOH
(c) NH4OH
(d) C₂H₅OH

Question. Which of the following substance will not give carbon dioxide on treatment with dilute acid ?
(a) Marble
(b) Limestone
(c) Baking soda
(d) Lime

Question. Which of the following is/are true when HCl(g) is passed through water? 
(i) It does not ionise in the solution as it is a covalent compound.
(ii) It ionises in the solution.
(iii) It gives both hydrogen and hydroxyl ions in the solution.
(iv) It forms hydronium ion in the solution due to the combination of hydrogen ion with water molecule.
(a) Only (i)
(b) Only (iii)
(c) (ii) and (iv)
(d) (iii) and (iv)

Question. Baking soda is a mixture of:         
(a) Sodium carbonate and acetic acid
(b) Sodium carbonate and tararic acid
(c) Sodium hydrogen carbonate and tartaric acid
(d) Sodium hydrogen carbonate and acetic acid

Question. Which of the following gives the correct increasing order of acid strength?   
(a) Water < acetic acid < hydrochloric acid
(b) Water < hydrochloric acid < acetic acid
(c) Acetic acid < water < hydrochloric acid
(d) Hydrochloric acid < water < acetic acid

Question. Which among the following is not a base?       
(a) NaOH
(b) KOH
(c) NH4OH
(d) C2H5OH

Question. Identify the correct representation of reaction occurring during chloralkali process.     
(a) 2NaCl(l) + 2H₂O(l) → 2NaOH(l) + Cl₂(g) + H₂(g)
(b) 2NaCl(l) + 2H₂O(aq) → 2NaOH(aq) + Cl₂(g) + H₂(aq)
(c) 2NaCl(aq) + 2H₂O(l) → 2NaOH(aq) + Cl₂(aq) + H₂(aq)
(d) 2NaCl(aq) + 2H₂O(l) → 2NaOH(aq) + Cl₂(g) + H₂(g)

Question. Equal volumes of hydrochloric acid and sodium hydroxide solutions of the same concentration are mixed and the pH of the resulting solution is checked with a pH paper. What would be the color obtained? (You may use color guide in the figure given below).       
(a) Red
(b) Yellow
(c) Yellowish green
(d) Blue

Question. Which of the following statements is true for acids?           
(a) Bitter and change red litmus to blue.
(b) Sour and change red litmus to blue.
(c) Sour and change blue litmus to red.
(d) Bitter and change blue litmus to red.

Question. What happens when the solution of an acid is mixed with the solution of a base in a test tube?     
(i) The temperature of the solution increases
(ii) The temperature of the solution decreases
(iii) The temperature of the solution remains the same
(iv) Salt formation takes place
(a) Only (i)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (i) and (iv)

Question. If 10 mL of H₂SO₄ is mixed with 10 mL of Mg(OH)₂ of the same concentration, the resultant solution will give the following colour with universal indicator:   
(a) Red
(b) Yellow
(c) Green
(d) Blue

Question. To protect tooth decay we are advised to brush our teeth regularly. The nature of the toothpaste commonly used is: 
(a) Acidic
(b) Neutral
(c) Basic
(d) Corrosive

Question: When hydrogen chloride gas is prepared on a humid day, the gas is usually passed through the guard tube containing calcium chloride. The role of calcium chloride taken in the guard tube is to
(a) absorb the evolved gas
(b) moisten the gas
(c) absorb moisture from the gas
(d) absorb Cl– ions from the evolved gas 

Question: In terms of acidic strength, which one of the following is in the correct increasing order?
(a) Water < Acetic acid < Hydrochloric acid
(b) Water < Hydrochloric acid < Acetic acid
(c) Acetic acid < Water < Hydrochloric acid
(d) Hydrochloric acid < Water < Acetic acid   

Question: Which one of the following salts does not con-tain water of crystallisation?
(a) Blue vitriol
(b) Baking soda
(c) Washing soda
(d) Gypsum 

Question: What is formed when zinc reacts with sodium hydroxide?
(a) Zinc hydroxide and sodium
(b) Sodium zincate and hydrogen gas
(c) Sodium zinc-oxide and hydrogen gas
(d) Sodium zincate and water 

Question: What happens when a solution of an acid is mixed with a solution of a base in a test tube?
(i) Temperature of the solution decreases
(ii) Temperature of the solution increases
(in) Temperature of the solution remains the same
(iv) Salt formation takes place
(a) (i) and (iv)
(b) (i) and (iii)
(c) (ii) only
(d) (ii) and (iv)   

Question: Brine is an
(a) aqueous solution of sodium hydroxide
(b) aqueous solution of sodium carbonate
(c) aqueous solution of sodium chloride
(d) aqueous solution of sodium bicarbonate 

Question: Tomato is a natural source of which acid?
(a) Acetic acid
(b) Citric acid
(c) Tartaric acid
(d) Oxalic acid 

Question: At what temperature is gypsum heated to form Plaster of Paris?
(a) 90°C
(b) 100°C
(c) 110°C
(d) 120°C 

Question: How many water molecules does hydrated cal-cium sulphate contain?
(a) 5
(b) 10
(c) 7
(d) 2 

Question: Na₂CO₃ . 10H₂O is
(a) washing soda
(b) baking soda
(c) bleaching powder
(d) tartaric acid   

Question: Sodium carbonate is a basic salt because it is a salt of a
(a) strong acid and strong base
(b) weak acid and weak base
(c) strong acid and weak base
(d) weak acid and strong base 

Question: Which of the following statements is correct about an aqueous solution of an acid and of a base?
(i) Higher the pH, stronger the acid
(ii) Higher the pH, weaker the acid
(iii) Lower the pH, stronger the base
(iv) Lower the pH, weaker the base
(a) (i) and (iii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) (ii) and (iv) 

Question: The apparatus given in the adjoining figure was set up to demonstrate electrical conductivity.
Which of the following statement(s) is (are) correct?
(i) Bulb will not glow because electrolyte is not acidic.
(ii) Bulb will glow because HCl is a strong acid and furnishes ions for conduction.
(iii) Bulb will not glow because circuit is incomplete.
(iv) Bulb will not glow because it depends upon the type of electrolytic solution.
(a) (i) and (iii)
(b) (ii) and (iv)
(c) (ii) only
(d) (iv) only   

Question: Alkalis are
(a) acids, which are soluble in water
(b) acids, which are insoluble in water
(c) bases, which are insoluble in water
(d) bases, which are soluble in water 

Question: Nettle sting is a natural source of which acid?
(a) MetiWanoic acid
(b) Lactic acid
(c) Citric acid
(d) Tartaric acid 

Question: Tooth enamel is made up of
(a) calcium phosphate
(b) calcium carbonate
(c) calcium oxide
(d) potassium 

Question: Lime water reacts with chlorine to give
(a) bleaching powder
(b) baking powder
(c) baking soda
(d) washing soda 

Question: Rain is called acid rain when its:
(a) pH falls below 7
(b) pH falls below 6
(c) pH falls below 5.6
(d) pH is above 7 

Question: Sodium hydroxide is a
(a) weak base
(b) weak acid
(c) strong base
(d) strong acid 

Question: What is the pH range of our body?
(a) 7.0 – 7.8
(b) 7.2 – 8.0
(c) 7.0 – 8.4
(d) 7.2 – 8.4 

Question: An aqueous solution turns red litmus solution blue. Excess addition of which of the following solution would reverse the change?
(a) Baking powder
(b) Lime
(c) Ammonium hydroxide solution
(d) Hydrochloric acid   

Question: Sodium hydroxide is used
(a) as an antacid
(b) in manufacture of soap
(c) as a cleansing agent
(d) in alkaline batteries 

Question: Sodium hydroxide turns phenolphthalein solution
(a) pink
(b) yellow
(c) colourless
(d) orange 

Question: When copper oxide and dilute hydrochloric acid react, colour changes to
(a) white
(b) bluish-green
(c) blue-black
(d) black

Question: Which of the following is not a acidic salt?
(a) CuSO₄
(b) NH₄Cl
(c) FeCl₃
(d) CH₃COONa   

Question. Which of the following statements is correct about an aqueous solution of an acid and a base?     
(i) The higher the pH, the stronger the acid
(ii) The higher the pH, the weaker the acid
(iii) The lower the pH, the stronger the base
(iv) The lower the pH, the weaker the base
(a) (i) and (iii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) (ii) and (iv)

Fill in the blanks

(a) The pH of the gastric juices released during digestion is ……………… .

(b) When acid reacts with a metal, ……………… gas is evolved.

(c) On heating gypsum, it loses water molecules and form ……………… .

Match the following
Column I                                Column II
(a) Bleaching powder        (i) Preparation of glass
(b) Baking soda                 (ii) Production of H₂ and Cl₂
(c) Washing soda              (iii) Decolourisation
(d) Sodium chloride          (iv) Antacid

Assertion and Reasoning Based Questions

Directions : In the following questions, a statement of assertion is followed by a statement of reason. Mark the correct choice as :
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of assertion.
(c) If assertion is true, but reason is false.
(d) If assertion is false but reason is true.

Question. Assertion : Calcium starts floating when added in water.
Reason : Calcium starts floating because the bubbles of oxygen gas which are formed during the reaction stick to the surface of the metal.
Answer : (c) Hydrogen gas is released when calcium reacts with water. Calcium starts floating because the bubbles of hydrogen gas which are formed during the reaction stick to the surface of the metal. As a result, calcium starts floating on water. Thus assertion is true, but reason is false.

Question. Assertion : Dry HCl gas does not change the colour of the dry litmus paper.
Reason : It is because dry HCl does not contain the OH– ions.
Answer : (c) Colour of the litmus paper is changed by the hydrogen ions. Dry HCl gas does not contain H+ions. Acids give hydrogen ions only in the presence of ions. In case of dry litmus paper and dry HCl, water is not present. Therefore, the colour of the litmus paper does not change. Thus assertion is true, but reason is false.

Question. Assertion : Tap water conducts electricity but distilled water does not conducts electricity.
Reason : Tap water contains ions whereas distilled water does not contain ions.
Answer : (a) Tap water conducts electricity as it contains ions whereas distilled water does not contain ions. Thus both assertion and reason are true and reason is the correct explanation of the assertion 

Question. Assertion : Curd and sour substances should not be stored in copper vessels.
Reason : Curd and other sour substances should not be kept in brass and copper vessels as they contain acids.
Answer : (a) When curd and sour substance are kept in brass and copper vessels, the metal reacts with the acid to liberate hydrogen gas and harmful products are obtained due to which the food gets spoiled. Thus both assertion and reason are true and reason is the correct explanation of the assertion.

Question. Assertion : Solutions of compounds like alcohol and glucose do not show acidic character. 
Reason : They do not show acidic character because they do not dissociate into ions.
Answer : (a) Solutions of compounds like alcohol and glucose do not show acidic character because like acids such as HCl which dissociates into H+ and Cl– ion these solutions do not dissociate into ions. Thus both assertion and reason are true and reason is the correct explanation of the assertion.

Creating Based Questions

Question. (a) Yellow stain of an Indian style vegetable curry on a white cloth turns reddish brown on application of soap on the cloth. What is the reason behind ?
(b) What is the colour of litmus solution when it is neither acidic nor basic ?
Answer : (a) The yellow stain contains turmeric (used as ingredient in most of the Indian curries) which is a natural indicator and it changes its colour from yellow to reddish brown when soap, which is basic in nature and is applied on the moist or wet cloth.
(b) Litmus solution is purple in colour when it is neither acidic nor basic.

Question. In a reaction of sodium chloride and sulphuric acid, hydrochloric acid is obtained as a gaseous product however, the evolved gas fails to turn the blue litmus paper red. What could be the reason ? But, if the litmus paper to be used is made moist prior hand, the evolved gas turns the moist litmus paper to red colour. Explain the observations.
Answer : The reaction can be shown as follows :

Hydrochloric acid in gaseous state is unionised hence cannot furnish the H+ ions, hence there is no reaction and colour change with litmus paper. On the other hand, when exposed to moist litmus paper, the hydrochloric acid gas reacts with water molecules present on paper and furnishes H+ ions which then react with litmus paper and changes its colour to red.

Question. A chemical compound X is prepared using sodium chloride as starting material. The compound X is used for faster cooking. It is also found as an ingredient in medicine to treat indigestion.
(a) Identify the compound X.
(b) Give an equation for the chemical reaction which takes place upon heating X during cooking.
(c) Which quality of compound X makes it suitable for treating indigestion ?
Answer : (a) Compound X is sodium hydrogen carbonate, NaHCO₃.

(c) NaHCO₃ is a mild non-corrosive base and can be used to neutralise acid. Indigestion caused by increased acidity in stomach can be reduced by consuming medicine containing NaHCO₃.

Question. A soil sample solution was analysed with universal pH indicator paper and the colour of the paper turned yellowish.
(a) What is the nature of soil ?
(b) What type of substance should the farmer add to the soil in order to get a suitable soil for farming ?
Answer : (a) As the soil solution turned universal indicator paper yellow, it indicates that the soil solution is acidic and contains a higher H+ ion concentration.
(b) The farmer should add some basic additives to soil such as slaked lime (calcium hydroxide) or quick lime (calcium oxide) to enhance the productivity of the soil.

Question. A student prepared a special ink using some basic chemical compound. The colour of the ink is blue.
The imprints marked on white paper using this ink turn invisible when the paper is heated slightly and the imprints reappear when the paper is kept outside for some time. Explain the observations. 
Answer : The chemical compound being used by the student is hydrated copper sulphate (CuSO₄.5H₂O) which is blue in colour. On heating it loses its water of crystallization and becomes white in colour, hence white colour on white paper becomes invisible. When the paper is left exposed to atmosphere, CuSO₄ crystals again absorb water from surrounding and turn blue in colour.

Paragraph/Table and Case Study Based Questions

Read the following and answer any four questions from 1(i) to 1(v):
Reshma broke her leg in an accident. She went to see the Dr. Sant Prakash. On examination, Dr. Prakash mixed the white power in water and applied to her leg along with the cotton and gauze. After a while, it turned into white, solid, hard mass. He said that it would support her fractured bone in the right position.

(i) After treatment, the doctor repacked the white powder back into moisture proof, airtight container. Why?
(a) The fungus growth will occur in open 
(b) The powder would react to moisture and turn into solid mass
(c) The powder with react to sunlight and turn into solid mass
(d) To prevent the stealing of the powder as it is very expensive

(ii) What is ‘white, solid hard mass’ called as?
(a) Talcum powder
(b) Paris of Plaster
(c) Plaster of Paris
(d) Copper sulphate

(iii) The reaction involved in the formation of white mass is :
(a) Combustion
(b) Oxidation
(c) Mineralisation
(d) Crystallisation

(iv) The graph shows the porosity and expansion of plaster with respect to water content. At what temperature, the reaction would occur?

(a) 373K
(b) 673K
(c) 273K
(d) 573K

(v) Study the following reaction and choose the correct option:

(a) Reactant is calcium hemihydrate, product is Gypsum
(b) Reactant is Gypsum, product is calcium hemihydrate
(c) Reactant is Gypsum, product is calcium sulphate hemihydrate
(d) Reactant is calcium sulphate hemihydrate, product is Gypsum

Read the following and answer any four questions from 2(i) to 2(v):
Harsha collected various solutions. Using a pH paper, she found out the approximate pH values of the solutions. She labelled the solutions as A, B, C, D and E, and presented their pH values on a line graph.
Observe the line graph carefully and answer the following questions.

(i) Which of the following could be solution A?
(a) Carrot juice
(b) Sodium hydroxide solution
(c) Water
(d) Gastric juice

(ii) Which one of the following statements is correct?
(a) Solution C is basic in nature.
(b) Solution B is more acidic than A.
(c) Solution D is more basic than E.
(d) Solution A is neutral in nature.

(iii) Which of the following could be the solution B?
(a) Blood
(b) Lemon juice
(c) HCl
(d) Coffee

(iv) What colour had pH strip shown with solution D?
(a) Red
(b) Yellow
(c) Violet
(d) Green

(v) Which one of the following arrangements is representing increasing concentration of H+ ions in the solution?
(a) A < B < C < D < E
(b) D < E < B < C < A
(c) A < C < B < E < D
(d) E < D < C < B < A

3. Sodium chloride is known as common salt. Its main source is sea water. It is also exists in the form of rocks and is called rock salt. Common salt is an important component of our food. It is also used for preparing
sodium hydroxide, baking soda, washing soda etc. Sodium Hydroxide is prepared by passing electricity through an aqueous solution of sodium chloride also known as brine. This process is known as chloralkali process. It is white translucent solid. Crystals of sodium hydroxide are deliquescent. It is readily soluble in water and gives strong alkaline solution.
Washing Soda is sodium carbonate decahydrate. It is prepared by heating baking soda. Recrystallisation of sodium carbonate gives a compound, which is used for removing permanent hardness of water. It is used in glass, soap and paper industries. It can be used as a cleaning agent for domestic purposes.
Plaster of Paris is is obtained by heating Gypsum upto 373K. On treatment with water it is again converted into gypsum and sets as a hard mass. It is used by doctors for setting fractured bones. It is used for making statues, models and other decorative materials.

(a) What is the chemical formula of plaster of paris?
(b) Name the chemical compound obtained by the recrystallization of sodium carbonate.
(c) Name the solution that is used to prepare caustic soda.
(d) Which of these statements is incorrect?
(i) On treatment with water plaster of paris is again converted into gypsum.
(ii) Crystals of sodium hydroxide are deliquescent.
(iii) Sodium chloride is known as common salt.
(iv) Plaster of Paris is calcium sulfate hydrates.
Answer : (a) CaSO₄.1/2H₂O.
(b) Recrystallization of sodium carbonate gives washing soda.
(c) Brine solution is used prepare caustic soda.
(d) The correct chemical name of plaster of paris is calcium sulfate hemihydrates.
Hence, the incorrect option is (iv).

4.

(a) What does column I represents ?
(b) What does column II represents ?
(c) Name one source of citric acid.
(d) What is released by ant’s sting ?
Answer : (a) Column I represents acids.
(b) Column II represents bases.
(c) Oranges are good source of citric acid.
(d) Formic acid is released by ant’s sting.

5.

(a) State the difference between an acid and base.
(b) What is the color of litmus paper for test tube I ?
(c) Give one example of the solution that could be present in test tube II.
(d) What is the color of litmus paper for test tube III ?
Answer : (a) Acids release hydronium ions in the solution and bases give hydroxide ions in aqueous solution.
(b) The color of litmus paper for test tube I is green.
(c) Solution of vinegar in water is a example of solution that could be present in test tube II.
(d) The color of litmus paper for test tube III is blue.

6.

(a) Give one use of plaster of paris.
(b) Give chemical formula of baking soda.
(c) State difference between baking soda and washing soda.
(d) Give chemical formula of slaked lime.
Answer : (a) Plaster of Paris is used for making statues, models and other decorative materials.
(b) The chemical formula of baking soda is NaHCO₃.
(c) Sodium hydrogen carbonate (NaHCO₃) is known as baking soda whereas Sodium carbonate
(Na₂CO₃) is known as washing soda.
(d) The chemical formula of slaked lime is Ca(OH)₂.

7.

(a) What is the nature of bleach ?
(b) What is color of litmus for lemon juice ?
(c) What is the pH value for neutral solutions ?
(d) Name the substances that would turn red litmus blue.
Answer : (a) Bleach is basic in nature.
(b) Lemon juice turns blue litmus red.
(c) The pH value for neutral solutions is 7.
(d) Detergent and bleach would turn red litmus blue