Lakhmir singh solutions chemistry class 10 Solutions for Chapter 2 chapter 2 acids bases and salts

What colour do the following indicators turn when added to a base or alkali (such as sodium hydroxide)?

(a) Methyl orange (b) litmus (c) red cabbage extract

(a)Why do acids not show acidic behaviour in the absence of water?

(b)Why does an aqueous solution of an acid conduct electricity?

(c)Why does distilled water not conduct electricity whereas rain water does?

Why should curd and other sour food stuffs (like lemon, juice, etc.) not be kept in metal containers (such as copper and brass vessels) ?

What is a neutralisation reaction? Explain with an example. Give the chemical equation of the reaction which takes place.

Why do HCl, H₂SO_4, HNO₃ , etc., show acidic character in aqueous solutions while solutions of compounds like C₆H₁₂O₆ (glucose) and C₂H₅OH (alcohol) do not show acidic character?

What is meant by strong acids and weak acids? Classify the following into strong acids and weak acids :

HCl, CH₃COOH, H₂SO₄, HNO₃, H₂CO₃, H₂SO₃

(a) What are organic acids and mineral acids?

(b) Give two examples each of organic acids and mineral acids.

(c) State some of the uses of mineral acids in industry.

What happens when an acid reacts with a metal oxide? Explain with the help of an example. Write a balanced equation for the reaction involved.

(a)What happens when dilute hydrochloric acid is added to sodium carbonate? Write balanced equation of the reaction involved.

(b)Which gas is liberated when dilute hydrochloric acid reacts with sodium carbonate? How will you test for the presence of this gas?

What is an olfactory indicator? Name two olfactory indicators. What is the effect of adding sodium hydroxide solution to these olfactory indicators?

While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?

What happens when an acid reacts with a metal hydrogen carbonate? Write equation of the reaction which takes place.

What happens when an acid reacts with a base? Explain by taking the example of hydrochloric acid and sodium hydroxide. Give equation of the chemical equation which takes place. What is the chemical name of such a reaction?

(a) What is produced if an acid is added to a base?

(b) Why does dry HCl gas not change the colour of dry litmus paper?

(c) What colour does phenolphthalein indicator turn when added to an alkali (such as sodium hydroxide)?

(a) What is an indicator? Name three common indicators.

(b) Name the acid-base indicator extracted from lichen.

(c) What colour does the turmeric paper turn when put in an alkaline solution?

Write word equations and then balanced equations for the reactions taking place when :

(a) dilute sulphuric acid reacts with zinc granules.

(b) dilute hydrochloric acid reacts with magnesium ribbon.

(c) dilute sulphuric acid reacts with aluminium powder.

(d) dilute hydrochloric acid reacts with iron filing

How is the concentration of hydronium ions (H₃O⁺) affected when the solution of an acid is dilute?

(a)What happens when an acid reacts with a metal? Give chemical equation of the reaction involved.

(b) Which gas is usually liberated when an acid reacts with a metal? How will you test for the presence of this gas?

Fill in the blanks in the following sentences :

(a) Acids have a _______ taste and they turn ___ litmus to ___.

(b) Substances do not show their acidic properties without ___.

(c) Acids produce ___ ions on dissolving in water.

(d) Those substances whose smell (or odour) changes in acidic or basic solutions are called ___ indicators.

(e) Onion and vanilla extract are ___ indicators.

Name one animal and one plant whose stings contain formic acid (or methanoic acid)

Name on natural source of each of the following acids:

(a) Citric acid (b) Oxalic acid

(c) Lactic acid (d) Tartaric acid

Complete and balance the following chemical equations:

(a) Zn(s) + HCl(aq) →

(b) Na2CO3(s) + HCl (aq) →

(c) NaHCO3(s) + 6 HCl →

(d) NaOH(aq) + HCl(aq) →

(e) CuO(s) + HCl (aq) →

How will you test for the gas which is liberated when hydrochloric acid reacts with an active metal?

Name the gas evolved when dilute HCl reacts with sodium hydrogen carbonate. How is it recognized?

Name an indicator which is pink in alkaline solution but turns colourless in acidic solution.

When a solution is added to vanilla extract, then the characteristic smell of vanilla cannot be detected. State whether the given solution is an acid or a base.

When a solution is added to a cloth strip treated with onion extract, then the smell of onion cannot be detected. State whether the given solution contains an acid or base.

Name an indicator which is red in acid solution but turns blue in basic solution.

Give the formulae of two strong acids and two weak acids.

What colours do the following indicators turn when added to an acid (such as hydrochloric acid)

(a) Litmus (b) methyl orange

With the help of labeled diagrams, describe an activity to show that acids produce ions only in aqueous solutions.

10 ml of a solution of NaOH is found to be completely neutralised by 8ml of a given solution of HCl. If we take 20 ml of the same solution of NaOH, the amount of HCl solution (the same solution as before) required to neutralise it will be :

(a) 4 ml

(b) 8ml

(c)12 ml

(d) 16ml

(b) Compounds such as alcohol and glucose also contain hydrogen but are not categorized as acids. Describe an activity to prove it.

(a) Which element is common to all acids?

(b) What happens when carbon dioxide gas is passed through lime water?

(i) For a short time?

(ii) For a considerable time?

Write equations of the reactions involved.

(a) What happens when an acid reacts with a metal carbonate? Explain with the help of an example. Give chemical equation of the reaction involved.

What happens to (a) the H⁺ ions, and (b) temperature of the solution, when an acid is neutralized?

What is the pH of a neutral solution?

Why does tooth decay start when the pH of mouth is lower than 5.5?

What is common in all the water soluble bases (or alkalis)?

What is the common name of water soluble bases?

Name the gas evolved when zinc granules are treated/heated with:

(a) Hydrochloric acid solution

(b) Sodium hydroxide solution

How is neutralization of a carbonate with an acid different from the neutralisation of an oxide or a hydroxide?

You have been provided with three test-tubes. One of these test -tubes contain distilled water and the other two contain an acidic and a basic solution respectively. If you are given only blue litmus paper, how will you identify the contents of each test-tube?

A white shirt has a yellow stain of curry. When soap is rubbed on this shirt during washing, the yellow stain turns reddish-brown. On rinsing the shirt with plenty of water , the reddish-brown stain turns yellow again.

(a) Name the natural indicator present in curry stain.

(b) Explain the change in colour of this indicator which takes place during washing and rinsing the shirt.

(c) What is the nature of soap(acidic/basic) as shown by the indicator present in the curry?

On adding dilute hydrochloric acid to copper oxide powder, the solution formed is blue-green.

(a) Predict the new compound formed which imparts a blue-green colour to solution.

(b) Write a balanced chemical equation of the reaction which takes place.

(c) On the basis of the above reaction, what can you say about the nature of copper oxide?

If someone is suffering from the problem of acidity after overeating, which of the following would suggest as remedy?

Lemon juice, Vinegar, Baking soda solution? Give reason for your choice.

When a piece of limestone reacts with dilute HCl, a gas X is produced. When gas X is passed through water, then a white precipitate Y is formed. On passing excess of gas X, the white precipitate dissolves forming a soluble compound Z.

(a) What are X, Y and Z?

(b) Write equations for the reactions which takes place:

(i) when limestone reacts with dilute HCl

(ii) when gas X reacts with limewater to form white precipitate Y.

(iii) when excess gas X dissolves white precipitate Y to form a soluble compound Z.

A substance X which is used as an antacid reacts with dilute hydrochloric acid to produce a gas Y which is used in one type of fire-extinguisher. Name the substance X and gas Y. Write a balanced equation for the chemical reaction which takes place.

The indicator which produces a pink colour in an alkaline solution:

(a) Methyl orange

(b) Turmeric paper

(c) Phenolphthalein

(d) Litmus paper

The property which is common between vinegar and curd is that they:

(a) Have sweet taste

(b) Have bitter taste

(c) Are tasteless

(d) Have sour taste

The discomfort caused by indigestion due to overeating can be cured by treating:

(a) Vinegar

(b) Lemon juice

(c) Baking soda

(d) Caustic soda

The indicators which turns red in acid solution are:

(a) Turmeric and litmus

(b) Phenolphthalein and methyl orange

(c) Litmus and methyl orange

(d) Phenolphthalein and litmus

A solution reacts with zinc granules to give a gas which burns with a ‘pop’ sound. The solution contains:

(a) Mg(OH)₂

(b) Na₂CO₃

(c) NaCl

(d) HCl

The property which is not shown by acids is :

(a) They have sour taste

(b) They feel soapy

(c) They turns litmus paper

(d) Their pH is less than seven

A solution reacts with marble chips to produce a gas which turns lime water milky. The solution contains:

(a) Na₂SO₄

(b) CaSO₄

(c) H₂SO₄

(d) K₂SO4

Which is more acidic: a solution of pH = 2 or a solution of pH = 6?

One of the following is not an organic acid. This is:

(a) Ethanoic acid

(b) Formic acid

(c) Citric acid

(d) Carbonic acid

Which of the following types of medicine is used for treating indigestion caused by over-eating?

(a) Antibiotic

(b) Analgesic

(c) Antacid

(d) Antiseptic

The pH of soil A is 7.5 while that of soil B is 4.5. Which of the two soils, A or B, should be treated with powdered chalk to adjust its pH and why?

Name the indicator which can give us an idea of how strong or weak an acid or base is.

Name the scientist who developed the pH scale.

(b) What happens during a wasp sting? What is its remedy?

Two solutions X and Y are tested with universal indicator. Solution X turns orange whereas solution Y turns red. Which of the solutions is a stronger acid?

(b) How does a universal indicator work?

(a) What is a universal indicator? For what purpose is it used?

(a) What happens during a bee sting? What is its remedy?

Fill in the following blanks with suitable words:

(a) Acids have a pH ______ than 7.

(b) Alkalis have a pH _____ than 7.

(c) Neutral substances have a pH of _____.

(d) The more acidic a solution, the _____ the pH.

(e) The more alkaline a solution, the ______ the pH.

Fresh milk has a pH of 6. When it changes into curd (yogurt), will its pH value increase or decrease? Why?

Two drinks P and Q gave acidic and alkaline reactions, respectively. One has a pH value of 9 and the other has a pH value of 3. Which drink has the pH value of 9?

Two solutions A and B have pH values of 3.0 and 9.5 respectively. Which of these will turn litmus solution from blue to red and which will turn phenolphthalein from colourless to pink?

Which chemical is injected into the skin of a person?

(a) During an ant’s sting?

(b) During the nettle leaf hair sting?

How can the effect of these stings be neutralised?

Two solutions X and Y have pH = 4 and pH = 8, respectively. Which solution will give alkaline reaction and which one acidic?

What colour will universal indicator show if you add it to the following substances?

(a) Potassium hydroxide, pH = 12

(b) Soda water, pH = 5

(c) Sulphuric acid, pH = 2

What is the name of the indicator which can be used for testing the pH of a solution?

(a) Explain the pH change as the cause of tooth decay. How can tooth decay caused by pH change be prevented?

(b) Explain how pH change in the lake water can endanger the lives of aquatic animals (like fish). What can be done to lessen the danger to the lives of aquatic animals in the lake?

(a) What would you expect the pH of pure water to be?

What ions are present in the solutions of following substances? (write the symbols only)

(i) Hydrochloric acid (ii) Nitric acid

(iii) Sulphuric acid (iv) Sodium hydroxide

(v) Potassium hydroxide (vi) Magnesium hydroxide

What is meant by strong bases and weak bases? Classify the following into strong bases and weak bases:

NH₄OH, Ca(OH)₂, NaOH, KOH, Mg(OH)₂

The soil in a field is highly acidic. Name two materials which can be added to this soil to reduce its acidity. Give the reason for your choice.

Which acid is produced in our stomach? What happens if there is an excess of acid in the stomach? How can its effect be cured?

(a) The pH of a cold drink is 5. What will be its action on blue and red litmus solutions?

(b) The pH values of three acids A, B and C having equal molar concentrations are 5.0, 2.8 and 3.5 respectively. Arrange these acids in order of the increasing acid strengths.

Under what soil conditions do you think a farmer would treat the soil of his fields with quicklime (calcium oxide), or slaked lime (calcium hydroxide) or chalk (calcium carbonate)?

(b) A farmer has found that the pH of soil in his fields is 4.2. Name any two chemical materials which he can mix with the soil to adjust its pH.

(a) What does the pH of a solution signify? Three solutions A, B and C have pH values of 6, 4 and 10 respectively. Which of the solutions is highly acidic?

(b) Why is it wrong to treat a wasp sting with baking soda solution?

(a) Why is it wrong to treat a bee sting with vinegar?

A beaker of concentrated hydrochloric acid has a pH of 1. What colour will full range universal indicator turn if it is added to this beaker? Is it a strong or a weak acid?

Which is more basic (or more alkaline): a solution of pH = 8 or a solution of pH = 11?

(c) How does an antacid work?

(d) Name two common antacids.

(b) What do you think will be the pH of an antacid solution: less than 7 or more than 7?

(a) What do you think will be the pH in the stomach of a person suffering from indigestion: less than 7 or more than 7?

Hydrochloric acid reacts with a metal X to form a gas Y which burns with a ‘pop’ sound. Sodium hydroxide solution also reacts with the same metal X (on heating) to form the same gas Y.

(a) Name X and Y

(b) Write the chemical equation of the reaction of metal X with (i) Hydrochloric acid, and (ii) Sodium hydroxide solution.

Separate the following into substances having pH values above and below 7. How do these influence litmus paper?

(i) Lemon juice (ii) Solution of washing soda (iii) Toothpaste (iv)Vinegar

(v) Stomach juices

A group of students measured the pH of some substances they found in their homes. Their results are given in the following table:

(a) What would the students have used to measure the pH ?

(b) Which solution is the most acidic?

(c) Which solution is the most alkaline?

(d) Which solutions are neutral?

(e) Which solution can be used to treat wasp stings?

(f) Which solution can be used to treat bee stings?

(a) Explain why the pH in a person’s mouth becomes lower after each meal.

(b) What damage could be caused while the pH is low?

(c) How could the person change his eating habits to lessen chances of suffering from tooth decay?

Solution A turns universal indicator blue to purple whereas solution B turns universal indicator orange to red.

(a) What will be the action of solution A on litmus?

(b) What will be action of solution B on litmus?

(c) Name any two substances which can give solutions like A.

(d) Name any two substances which can give solutions like B.

(e) What sort of reaction takes place when solution A reacts with solution B?

Here are some results of solutions tested with universal indicator paper:

Arrange the solutions in order of their increasing pH values (starting with the one with the lowest pH).

Potatoes grow well on Anhad’s farm which has soil with a pH of 5.5. Anhad decides to add lot of lime to soil so that he can grow broccoli in the same farm:

(a) Do potatoes grow better in acidic or alkaline soil?

(b) Does broccoli grow better in acidic or alkaline soil?

The pH values of five solutions A, B, C, D and E are given below:

Which solution is (i) weakly alkaline (ii) neutral (iii) strongly acidic (iv) strongly alkaline, and (v) weakly acidic?

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?

The daffodil plant grow best in soil having a pH range of 6.0 to6.5. If the soil in a garden has a pH of 4.5, which substance needs to be added to the soil in order to grow daffodils?

Solutions:

(a) Salt

(b) Lime

(c) Sand

(d) Compost

The acid produce naturally in our stomach is :

(a) Acetic acid

(b) Citric acid

(c) Hydrochloric acid

(d) Sulphuric acid

Fresh milk has a pH of 6. When milk changes into curd, the pH value will:

(a) Become 7

(b) Become less than 6

(c) Become more than 7

(d) Remain unchanged

It has been found that rubbing vinegar on the stung area of the skin of a person gives him relief. The person has been stung by:

(a) Wasp

(b) Ant

(c) Honey bee

(d) Nettle leaf hair

Wasp stings can be treated with:

(a) Baking soda

(b) Vinegar

(c) Washing soda

(d) Milk of magnesia

Bee stings can be treated with:

(a) Vinegar

(b) Sodium hydrogencarbonate

(c) Potassium hydroxide

(d) Lemon juice

Which of the following elements would form oxides which would indicate pH values less than seven, using moist pH paper?

Magnesium, Carbon, Sulphur, Hydrogen, copper

A solution turns Phenolphthalein indicator pink. The most likely pH of the solution will be:

(a) 6

(b) 4

(c) 9

(d) 7

A solution turns blue litmus red. Its pH is likely to be:

(a) 7

(b) 5

(c) 8

(d) 14

.A solution turns red litmus blue. Its pH is likely to be:

(a) 1

(b) 4

(c) 5

(d) 10

One of the following does not inject an acidic liquid into the skin through its sting. This is:

(a) Honey bee

(b) Ant

(c) Wasp

(d) Nettle leaf hair

Wasp sting contains:

(a) A sugar solution

(b) An acidic liquid

(c) A salt solution

(d) An alkaline liquid

Bee sting contains:

(a) An acidic liquid

(b) A salt solution

(c) An alkaline liquid

(d) An alcohol

One of the following is a medicine for indigestion. This is:

(a) Sodium hydroxide

(b) Manganese dioxide

(c) Magnesium hydroxide

(d) Potassium hydroxide

(a) What effect does the concentration of H⁺ (aq) ions have on the nature of a solution?

(b) What effect does the concentration of OH^– ions have on the nature of a solution?

(c) Someone put some universal indicator paper into vinegar. The pH is 3. What does this tell you about the vinegar?

(d) Someone put some universal indicator paper onto wet soap. The pH is 8. What does this tell you about the soap?

(e) State whether a solution is acidic, alkaline or neutral if its pH is :

(i) 9 (ii) 4 (iii) 7 (iv) 1 (v) 10 (vi) 3

(a) What happens when zinc granules are heated with sodium hydroxide solution? Write equation of the reaction which takes place.

(b) What happens when bases react with non-metal oxides? Explain with the help of an example. What does this reaction tell us about the nature of non-metal oxides?

(a) Define an acid and a base. Give two examples of each.

(b) Give the names and formulae of two strong bases and two weak bases.

(c) What type of ions are formed:

(i) when an acid is dissolved in water?

(ii) when a base (or alkali) is dissolved in water?

(d) Write the neutralisation reaction between acids and bases in terms of the ions involved.

(e) Write any two important uses of bases

(a) Do basic solutions also have H⁺ (aq) ions? If yes, then why are they basic?

(b) When a solution becomes more acidic, does the pH get higher or lower?

The colour of methyl orange indicator in a solution is yellow. The pH of the solution is likely to be:

(a) 7

(b) Less than 7

(c) 0

(d) More than 7

(a) The pH values of six solutions A to F are given below:

A = 0; B = 11, C = 6, D = 3, E = 13, F = 8

Which of the above solutions are (i) acids (ii) alkalis?

(b) Name the acids or alkalis used to make (i) car batteries (ii) explosives (iii) soaps (iv) fertilisers.

(b) What colour would the universal indicator show in an aqueous solution of sugar? Why?

A first-aid manual suggests that vinegar should be used to treat wasp stings and baking soda for bee stings.

What does this information tell you about the chemical nature of:

(a) Wasp stings ?

(b) Bee stings?

What is the chemical formula of (a) baking soda, and (b) washing soda.

(a) What is meant by “water of crystallisation” in a substance? Explain with an example.

(b) How would you show that blue copper sulphate crystals contain water of crystallisation?

(c) Explain how anhydrous copper sulphate can be used to detect the presence of moisture (water) in a liquid.

(a) What happens when copper sulphate crystals are heated strongly? Explain with the help of an example.

(b) What happens when a few drops of water are added to anhydrous copper sulphate? Explain with the help of an equation.

(a) What is the common name of sodium hydrogencarbonate?

(b) What happens when a solution of sodium hydrogencarbonate is heated? Write the equation of the reaction involved.

(c) Explain why, sodium hydrogencarbonate is used as an antacid.

State the common and chemical names of the compounds formed when plaster of Paris is mixed with water.

What happens when a cold and concentrated solution of sodium chloride reacts with ammonia and carbon dioxide? Write the chemical equation of the reaction which takes place.

Describe how sodium hydrogen carbonate (baking soda) is produced on a large scale. Write equation of the reactions involved.

What is baking soda? Write the chemical name of baking soda. Give the important uses of baking soda. How does baking soda differ chemically from washing soda?

Write the chemical formula of ammonium chloride. Explain why an aqueous solution of ammonium chloride is acidic in nature? Illustrate your answer with the help of a chemical equation.

Write the formulae of sodium chloride and sodium carbonate. Explain why an aqueous solution of sodium chloride is neutral but an aqueous solution of sodium carbonate is basic (or alkaline). Write chemical equations of the reactions involved.

What is washing soda? State two properties and two uses of washing soda.

Complete and balance the following equations:

(a) NaCl(aq) + H₂O(l) →

(b) 2NaHCO₃ →

(c) NaCl + NH₃ + H₂O + CO₂ →

(d) Ca(OH)₂ + Cl₂ →

During electrolysis of a saturated solution of sodium chloride, where is :

(a) Chlorine formed?

(b) Hydrogen formed?

(c) Sodium hydroxide formed?

ill in the following blanks:

(a) Common salt is obtained from seawater by the process of …….

(b) Rock salt is mined just like …….

(c) Chemical formula of washing soda is ……

(d) Sodium hydrogencarbonate is ………… soda whereas sodium carbonate is …. Soda

(e) The chemical formula of plaster of Paris is ……

The electrolysis of an aqueous solution of sodium chloride gives us three products. Name them.

Name the raw material used for production of caustic soda.

Give any two uses of common salt (sodium chloride).

Name three chemicals made from common salt or sodium chloride.

Why is sodium chloride required in our body?

How is common salt obtained from sea water?

Name the major salt present in sea water.

What are the two main ways in which common salt (sodium chloride) occurs in nature?

Write the chemical name and formula of (a) common salt and (b) caustic soda.

What is the common name of (a) NaHCO₃ and (b) Na₂CO₃.10H₂O

Which compound is used as an antacid in medicine: NaHCO₃ or Na₂CO₃?

Name the metal whose carbonate is known as washing soda.

Name an acid which is present in baking powder.

Name a metal carbonate which is soluble in water.

Name a sodium compound which is a constituent of many dry soap powders.

Name a calcium compound which hardens on wetting with water.

Name the product formed when Cl₂ and H₂ produced during electrolysis of brine are made to combine.

What is the commercial name of calcium sulphate hemihydrate?

With which substance should chlorine be treated to get bleaching powder?

Name the salt which is used as preservative in pickles, and in curing meat and fish.

What would be the colour of litmus in a solution of sodium carbonate?

Which of the following salt has a blue colour and why?

CuSO₄.5H₂O or CuSO₄.

(a) What will happen if heating is not controlled while preparing Plaster of Paris?

(b) Write an equation to show the reaction between plaster of Paris and water.

Write the chemical formula of (i) soda ash and (ii) sodium carbonate decahydrate.

State whether the following statement is true or false:

Copper sulphate crystals are always wet due to the presence of water of crystallisation in them.

State two uses each of the following compounds:

(a) Sodium hydroxide (b) Chlorine

(c) Hydrogen (d) Hydrochloric acid.

(a) What is gypsum ? What happens when gypsum is heated to 100℃ (373K)?

(b) Name a sodium compound which is used for making borax and glass.

(c) Name the compound which is used in hospitals for setting fractured bones.

(d) Which is the real bleaching powder agent in the bleaching powder?

(a) Name a sodium compound used for softening hard water.

(b) Which compound of calcium is used for disinfecting drinking water supply?

(c) Name a metal compound which has detergent properties (cleansing properties).

(d) Name one compound of calcium which is used for removing colour of a coloured cloth.

(e) State a peculiar (or remarkable) property of plaster of Paris.

(f) Name the substance obtained by the action of chlorine on solid (dry) slaked lime.

(a) What is “baking powder”? How does it make the cake soft and spongy?

(b) In addition to sodium hydrogencarbonate, baking powder contain a substance X. Name the substance. What is the role of substance X in the baking powder?

The formula of baking soda is:

(a) K₂CO₃

(b) KHCO₃

(c) NaHCO₃

(d) KNO₃

Which of the following salt will give an aqueous solution having pH of almost 7?

(a) NH₄NO₃

(b) NH₄Cl

(c) CaCl₂

(d) KCl

The number of molecules of water of crystallisation present in washing soda crystals is:

(a) Five

(b) Two

(c) Ten

(d) Seven

A salt whose aqueous solution will have a pH of more than 7 will be:

(a) K₂CO₃

(b) K₂SO₄

(c) NaCl

(d) NH₄Cl

Plaster of paris is prepared by heating one of the following to a temperature of 100℃. This is:

(a) CaSO_3.2H₂O

(b) CaCl₂.2H₂O

(c) CaCO₃.2H₂O

(d) CaSO_4.2H₂O

Which of the following is treated with chlorine to obtain bleaching powder?

(a) CaSO₄

(b) Ca(OH)₂

(c) Mg(OH)₂

(d) KOH

A salt is dissolved in water and the pH of this salt solution is measured with a universal indicator paper. If the pH of the solution is less than 7, the salt is most likely to be:

(a) CH₃COONa

(b) Na₂CO₃

(c) KCl

(d) NH₄Cl

The aqueous solution of one of the following salt will turn phenolphthalein indicator pink. This salt is:

(a) KCl

(b) K₂SO₄

(c) K₂CO₃

(d) KNO₃

The salt whose aqueous solution will have no effect on either red litmus or blue litmus is

(a) Potassium sulphate

(b) Sodium carbonate

(c) Ammonium sulphate

(d) Sodium acetate

The salt whose aqueous solution will turn blue litmus to red is:

(a) Ammonium sulphate

(b) Sodium acetate

(c) Sodium chloride

(d) Potassium carbonate

(a) What is plaster of Paris? Write the chemical formula for plaster of Paris.

(b) How is plaster of Paris prepared? Write chemical equation of the reaction involved.

(c) Explain why plaster of Paris should be stored in a moisture-proof container.

(d) Write two important uses of plaster of Paris.

**The products of chlor-alkali process are:**

**(a) NaCl, Cl₂ **, and H₂****

**(b) Cl₂ **, H₂** **and NaOH****

**(c) Cl₂, Na₂CO₃ **and H₂O****

**(d) NaOH, Cl₂ **and HCl****

The aqueous solution of one of the following salt will turn red litmus to blue. This salt is:

(a) Potassium sulphate

(b) Sodium sulphate

(c) Sodium chloride

(d) Potassium carbonate

The salt which give a neutral solution on dissolving in water will be:

(a) CH₃COONa

(b) NH₄Cl

(c) KCl

(d) Na₂CO₃

The salt which will give an acidic solution on dissolving in water is:

(a) KCl

(b) NH₄Cl

(c) Na₂CO₃

(d) CH₃COONa

(a) What is a salt? Give the names and formulae of any two salts. Also name the acids and bases from which these salts may be obtained.

(b) What is meant by ‘a family of salts’? Explain with examples.

(c) What is meant by ‘hydrated’ and ‘anhydrous’ salts? Explain with examples.

(d) Write the names, formulae and colours of any two hydrated salts.

(e) What will be the colour of litmus in an aqueous solution of ammonium chloride salt?

What name is given to the common salt which is mined from underground deposits? How was this salt mined?

(a) What is bleaching powder? How is bleaching powder prepared? Write chemical equation of the reactions involved.

(b) What happens when bleaching powder reacts with dilute sulphuric acid? Give equation of the reaction involved.

(c) Write two important uses of bleaching powder.

(a) What happens when a concentrated solution of sodium chloride (brine) is electrolysed? Write the equation of the reaction involved.

(b) Why is the electrolysis of a concentrated solution of sodium chloride known as chlor-alkali process?

(c) Name three products of the chlor-alkali process. State two uses of each of these products.

(a) What is the common name of the compound CaOCl₂?

(b) Name the raw material used for the preparation of plaster of Paris.

(c) Which property of plaster of Paris is utilised in making casts for broken limbs in hospitals?

(d) Explain why chlorine is used for sterilising drinking water supply.

What does a soda-acid type fire extinguisher contain? How does it work? Explain the working of acid fire extinguisher with the help of labeled diagram.

(a) What is the chemical name of bleaching powder?

(b) What is the chemical formula of bleaching powder?

(c) What are the materials used for the preparation of bleaching powder?

(d) State one use of bleaching powder (other than bleaching).

(a) Describe how washing soda is produced starting from sodium chloride (common salt). Write equations of all the reactions involved.

(b) State whether an aqueous solution of washing soda is acidic or alkaline. Give reason for your answer.

(c) What is meant by saying that washing soda has detergent properties?

(d) Mention two important uses of washing soda (or sodium carbonate).

(a) Name two constituents of baking powder.

(b) How does baking powder differ from baking soda?

(c) Explain the action of baking powder in the making of cake (or bread). Write equation of the reaction involved.

One of the following salt will give an alkaline solution on dissolving in water. This is:

(a) Na₂CO₃

(b) Na₂SO₄

(c) NaCl

(d)(NH₄)₂SO₄