CLASS 10 Science CHAPTER 3 METALs AND NON- METALs (NCERT Solution)

CLASS 10 Science 
CHAPTER 3 
METALs AND NON- METALs (NCERT Solution)

Question 1: Explain the meanings of malleable and ductile.

Answer: Malleable: Substances that can be beaten into thin sheets are called malleable. For example, most of the metals are malleable.

Ductile: Substances that can be drawn into thin wires are called ductile. For example, most of the

metals are ductile.

Question 2: Why is sodium kept immersed in kerosene oil?

Answer: Sodium and potassium are very reactive metals and and combine explosively with air as well as water. Hence, they catch fire if kept in open. Therefore, to prevent accidental fires and accidents, sodium is stored immersed in kerosene oil.

Question 3: Write equations for the reactions of

(i) iron with steam

(ii) calcium and potassium with water

Answer: 

Question 4: Samples of four metals A, B, C and D were taken and added to the following solution

one by one. The results obtained have been tabulated as follows.

MetalIron (II) sulphateCooper (II) sulphateZinc sulphate Silver nitrate

A.     No reaction          Displacement

B.     Displacement       No reaction

C.     No reaction          No reaction          No reaction            Displacement

D.     No reaction          No reaction          No reaction            No reaction

Use the Table above to answer the following questions about metals A, B, C and D.

(i) Which is the most reactive metal?

(ii) What would you observe if B is added to a solution of copper (II) sulphate?

(iii) Arrange the metals A, B, C and D in the order of decreasing reactivity.

Answer:

A + FeSO4 → No reaction, i.e., A is less reactive than iron

A + CuSO4 → Displacement, i.e., A is more reactive than copper

B + FeSO4 → Displacement, i.e., B is more reactive than iron

B + ZnSO4 → No reaction, i.e., B is less reactive than zinc

C + FeSO4 → No reaction, i.e., C is less reactive than iron

C + CuSO4 → No reaction, i.e., C is less reactive than copper

C + ZnSO4 → No reaction, i.e., C is less reactive than zinc

C + AgNO3 → Displacement, i.e., C is more reactive than silver

D + FeSO4/CuSO4/ZnSO4/AgNO3 → No reaction, i.e., D is less reactive than iron, copper, zinc, and silver

From the above equations, we obtain:

(i) B is the most reactive metal.

(ii) If B is added to a solution of copper (II) sulphate, then it would displace copper.

B + CuSO4 → Displacement

(iii) The arrangement of the metals in the order of decreasing reactivity is:

B > A > C > D

Question 5: Which gas is produced when dilute hydrochloric acid is added to a reactive metal?

Write the chemical reaction when iron reacts with dilute H2SO4.

Answer: Hydrogen gas is evolved when dilute hydrochloric acid is added to a reactive metal. When iron reacts with dilute H2SO4, iron (II) sulphate with the evolution of hydrogen gas is formed.

Question 6: What would you observe when zinc is added to a solution of iron (II) sulphate? Write

the chemical reaction that takes place.

Answer: Zinc is more reactive than iron. Therefore, if zinc is added to a solution of iron (II) sulphate, then it would displace iron from the solution.

Question 7: (i) Write the electron-dot structures for sodium, oxygen and magnesium.

(ii) Show the formation of Na2O and MgO by the transfer of electrons.

(iii) What are the ions present in these compounds?

Answer: (i) The representation of elements with valence electrons as dots around the elements is

referred to as electron-dot structure for elements.

(ii) 

(iii) The ions present in Na2O are Na+ and O2− ions and in MgO are Mg2+ and O2− ions.

Question 8: Why do ionic compounds have high melting points?

Answer: Ionic compounds have strong electrostatic forces of attraction between the ions. Therefore, it requires a lot of energy to overcome these forces. That is why ionic compounds have high melting points.

Question 9: Define the following terms.

(i) Mineral (ii) Ore (iii) Gangue

Answer: (i) Mineral:  Minerals are naturally occurring element or compounds in the earth's crust. Most of the elements occur in nature as in combined state as minerals. The chemical composition of minerals is fixed.

(ii) Ore: Minerals from which metals can be extracted profitably are known as ores.

(iii) Gangue: The impurities (sand, silt, soil, gravel, etc.) present in the ore are called gangue.

Question 10: Name two metals which are found in nature in the free state. 

Answer: The metals at the bottom of the reactivity series are mostly found in free state. For example: gold, silver, and platinum.

Question 11: What chemical process is used for obtaining a metal from its oxide?

Answer: The chemical process used for obtaining a metal from its oxide is reduction. In this process, metal oxides are reduced by using suitable reducing agents such as carbon or by highly reactive metals to displace the metals from their oxides.

For example, zinc oxide is reduced to metallic zinc by heating with carbon. 

Manganese dioxide is reduced to manganese by treating it with aluminium powder. In this case,  aluminium displaces manganese from its oxide.

Oxides of more reactive metals are reduced by electrolysis.

Question 12: Metallic oxides of zinc, magnesium and copper were heated with the following metals.

Metal                                Zinc     Magnesium       Copper

Zinc oxide                          -              -                        -

Magnesium oxide               -              -                        -

Copper oxide                      -               -                        -

In which cases will you find displacement reactions taking place?

Answer:  Metal       Zinc                   Magnesium              Copper

Zinc oxide                No reaction       Displacement           No reaction

Magnesium oxide     No reaction       No reaction              No reaction

Copper oxide            Displacement    Displacement           No reaction

Question 13: Which metals do not corrode easily?

Answer: More reactive a metal is, more likely it is to be corroded. Therefore, less reactive metals

are less likely to get corroded. This is why gold plating provides high resistance to corrosion.

Question 14: What are alloys?

Answer: Alloys are homogeneous mixtures of two or more elements. The elements could be two

metals, or a metal and a non-metal. An alloy is formed by first melting the metal and then dissolving the other elements in it. For example, steel is an alloy of iron and carbon.

 Question 15: Which of the following pairs will give displacement reactions?

(a) NaCl solution and copper metal

(b) MgCl2 solution and aluminium metal

(c) FeSO4 solution and silver metal

(d) AgNO3 solution and copper metal.

(d) AgNO3 solution and copper metal

Answer: (d) Since cupper is more reactive than silver so it will displace silver from silver nitrate.

Question 16: Which of the following methods is suitable for preventing an iron frying pan from

rusting?

(a) Applying grease

(b) Applying paint

(c) Applying a coating of zinc

(d) all of the above.

Answer: (c) Applying a coating of zinc (We can also apply grease and paint to prevent iron from rusting. However, in case of iron frying pan, grease and paint cannot be applied because when the pan will be heated and washed again and again, the coating of grease and paint would get destroyed.)

Question 17: An element reacts with oxygen to give a compound with a high melting point. This

compound is also soluble in water. The element is likely to be

(a) calcium

(b) carbon

(c) silicon

(d) iron

Answer: (a) The element is likely to be calcium

Question 18: Food cans are coated with tin and not with zinc because

(a) zinc is costlier than tin.

(b) zinc has a higher melting point than tin.

(c) zinc is more reactive than tin.

(d) zinc is less reactive than tin.

Answer: (c) Food cans are coated with tin and not with zinc because zinc is more reactive than tin.

Question 19: You are given a hammer, a battery, a bulb, wires and a switch.

(a) How could you use them to distinguish between samples of metals and non-metals?

(b) Assess the usefulness of these tests in distinguishing between metals and non-metals.

Answer: (a) With the hammer, we can beat the sample and if it can be beaten into thin sheets (that is, it is malleable), then it is a metal otherwise a non-metal. Similarly, we can use the battery, bulb, wires, and a switch to set up a circuit with the sample. If the sample conducts electricity, then it is a metal otherwise a non-metal.

(b) The above tests are useful in distinguishing between metals and non-metals as these are based on the physical properties. No chemical reactions are involved in these tests.

Question 20: What are amphoteric oxides? Give two examples of amphoteric oxides. 

Answer: Those oxides that behave as both acidic and basic oxides are called amphoteric oxides. Examples: aluminium oxide (Al2O3), zinc oxide (ZnO)

Question 21: Name two metals which will displace hydrogen from dilute acids, and two metals which will not.

Answer: Metals that are more reactive than hydrogen displace it from dilute acids. For example:

sodium and potassium. Metals that are less reactive than hydrogen do not displace it. For example:

copper and silver.

Question 22: In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?

Answer: In the electrolytic refining of a metal M:

Anode → Impure metal M

Cathode → Thin strip of pure metal M

Electrolyte → Solution of salt of the metal M

Question 23: Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in figure below.

(a) What will be the action of gas on

(i) dry litmus paper?

(ii) moist litmus paper?

(b) Write a balanced chemical equation for the reaction taking place.

Answer: (a) (i) There will be no action on dry litmus paper.

(ii) Since the gas is sulphur dioxide (SO2), it turns moist blue litmus paper to red because sulphur

dioxide reacts with moisture to form sulphurous acid.

(b) 

.

Question 24: State two ways to prevent the rusting of iron.

Answer: Two ways to prevent the rusting of iron are:

(i) Oiling, greasing, or painting: By applying oil, grease, or paint, the surface becomes water proof and the moisture and oxygen present in the air cannot come into direct contact with iron. Hence, rusting is prevented.

(ii) Galvanisation: An iron article is coated with a layer of zinc metal, which prevents the iron to come in contact with oxygen and moisture. Hence, rusting is prevented.

Question 25: What type of oxides is formed when non-metals combine with oxygen?

Answer: Non-metals combine with oxygen to form acidic oxides. 

For example:  

Question 26: Give reasons

(a) Platinum, gold and silver are used to make jewellery.

(b) Sodium, potassium and lithium are stored under oil.

(c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.

(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.

Answer: (a) Platinum, gold, and silver are used to make jewellery because they are very lustrous.

Also, they are very less reactive and do not corrode easily.

(b) Sodium, potassium, and lithium are very reactive metals and react very vigorously with air as well as water. Therefore, they are kept immersed in kerosene oil in order to prevent their contact with air and moisture.

(c) Though aluminium is a highly reactive metal, it is resistant to corrosion. This is because aluminium reacts with oxygen present in air to form a thin layer of aluminium oxide. This oxide layer is very stable and prevents further reaction of aluminium with oxygen. Also, it is light in weight and a good conductor of heat. Hence, it is used to make cooking utensils.

(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction because metals can be easily extracted from their oxides rather than from their carbonates and sulphides

Question 27: You must have seen tarnished copper vessels being cleaned with lemon or tamarind

juice. Explain why these sour substances are effective in cleaning the vessels.

Answer: Copper reacts with moist carbon dioxide in air to form copper carbonate and as a result,

copper vessel loses its shiny brown surface forming a green layer of copper carbonate. The citric acid present in the lemon or tamarind neutralises the basis copper carbonate and dissolves the layer. That is why, tarnished copper vessels are cleaned with lemon or tamarind juice to give the surface of the copper vessel its characteristic lustre.

Question 28: Differentiate between metal and non-metal on the basis of their chemical properties.

Answer: Metal

Metals are electropositive.

They react with oxygen to form basic oxides.

These have ionic bonds.

They react with water to form oxides and hydroxides. Some they do not react with water. metals react with cold water, some with hot water, and some with steam.

They react with dilute acids to form a salt and evolve hydrogen gas. However, Cu, Ag, Au, Pt, Hg do not react.

They react with the salt solution of metals. Depending on their reactivity, displacement reaction can occur.

They act as reducing agents (as they can easily lose electrons).

Non-metal

Non-metals are electronegative.

They react with oxygen to form acidic or neutral oxides.

These have covalent bonds.

They do not react with dilute acids. These are not capable of replacing hydrogen.

These react with the salt solution of non-metals.

These act as oxidising agents (as they can gain electrons).

Question 29: A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?

Answer: He must have dipped the gold metal in the solution of aqua regia − a 3:1 mixture of conc. HCl and conc. HNO3. Aqua regia is a fuming, highly corrosive liquid. It dissolves gold in it. After dipping the gold ornaments in aqua regia, the outer layer of gold gets dissolved and the inner shiny layer appears. That is why the weight of gold ornament reduced.

Question 30: Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).

Answer: Copper does not react with cold water, hot water, or steam. However, iron reacts with steam. If the hot water tanks are made of steel (an alloy of iron), then iron would react vigorously with the steam formed from hot water. 

That is why copper is used to make hot water tanks, and not steel.

CLASS 10 Science CHAPTER 2 ACIDs , BASEs AND SALTs (NCERT Solution)

CLASS 10 Science 

CHAPTER 2 

ACIDs , BASEs AND SALTs (NCERT Solution)

Question 1: 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. If you are given

only red litmus paper, how will you identify the contents of each test tube?

Answer: If the colour of red litmus paper gets changed to blue, then it is a base and if there is no colour change, then it is either acidic or neutral. Thus, basic solution can be easily identified. Let us mark the three test tubes as A, B, and C. A drop of the solution in A is put on the red litmus paper. Same is repeated with solution B and C. If either of them changes colour to blue, then it is basic. Therefore, out of three, one is eliminated. Out of the remaining two, any one can be acidic or neutral. Now a drop of basic solution is mixed with a drop of each of the remaining two solutions separately and then the nature of the drops of the mixtures is checked. If the colour of red litmus turns blue, then the second solution is neutral and if there is no change in colour, then the second solution is acidic. This is because acidic and basic solutions neutralize each other.

Question 2: Why should curd and sour substances not be kept in brass and copper vessels?

Answer: Curd and other sour substances contain acids. Therefore, when they are kept in brass and copper vessels, the metal reacts with the acid to liberate hydrogen gas and harmful products, thereby spoiling the food.

Question 3: Which gas is usually liberated when an acid reacts with a metal? Illustrate with an

example. How will you test for the presence of this gas?

Answer: Hydrogen gas is usually liberated when an acid reacts with a metal. Take few pieces of zinc granules and add 5 ml of dilute H2SO4. Shake it and pass the gas produced into a soap solution. The bubbles of the soap solution are formed. These soap bubbles contain hydrogen gas.

We can test the evolved hydrogen gas by its burning with a pop sound when a candle is brought

near the soap bubbles.

Question 4: Metal compound A reacts with dilute hydrochloric acid to produce effervescence.

The gas evolved extinguishes a burning candle. Write a balanced chemical equation for the

reaction if one of the compounds formed is calcium chloride.

Answer: 

Question 5: Why do HCl, HNO3, etc., show acidic characters in aqueous solutions while

solutions of compounds like alcohol and glucose do not show acidic character?

Answer:- The dissociation of HCl or HNO3 to form hydrogen ions always occurs in the presence of water. Hydrogen ions (H+) combine with H2O to form hydronium ions (H3O+). The reaction is as follows: 

Aqueous solutions of glucose and alcohol contain hydrogen, these cannot dissociate in water to form hydrogen ions. Hence, they do not show acidic character.

Question 6: Why does an aqueous solution of an acid conduct electricity?

Answer: Acids dissociate in aqueous solutions to form ions. These ions are responsible for

conduction of electricity.

Question 7: Why does dry HCl gas not change the colour of the dry litmus paper?

Answer: Colour of the litmus paper is changed by the hydrogen ions. Dry HCl gas does not

contain H+ ions. It is only in the aqueous solution that an acid dissociates to give ions. Since in

this case, neither HCl is in the aqueous form nor the litmus paper is wet, therefore, the colour of

the litmus paper does not change.

Since the process of dissolving an acid in water is exothermic, it is always recommended that acid

should be added to water. If it is done the other way, then it is possible that because of the large

amount of heat generated, the mixture splashes out and causes burns.

Question 8: How is the concentration of hydronium ions (H3O+) affected when a solution of an

acid is diluted?

Answer: When an acid is diluted, the concentration of hydronium ions (H3O+) per unit volume

decreases. This means that the strength of the acid decreases.

Question 9: How is the concentration of hydroxide ions (OH−) affected when excess base is

dissolved in a solution of sodium hydroxide?

Answer: The concentration of hydroxide ions (OH−) would increase when excess base is

dissolved in a solution of sodium hydroxide.

Question 10: You have two solutions, A and B. The pH of solution A is 6 and pH of solution B is 8. Which solution has more hydrogen ion concentration? Which of this is acidic and which one is basic?

Answer: A pH value of less than 7 indicates an acidic solution, while greater than 7 indicates a

basic solution. Therefore, the solution with pH = 6 is acidic and has more hydrogen ion concentration than the solution of pH = 8 which is basic.

Question 11: What effect does the concentration of H+ ions have on the nature of the solution?

Answer: Concentration H+ of can have a varied effect on the nature of the solution. With an increase in H+ ion concentration, the solution becomes more acidic, while a decrease of H+ ion causes an increase in the basicity of the solution.

Question 12: Do basic solutions also have H+ ions? If yes, then why are these basic?

Answer: Yes, basic solution also has H+ ions. However, their concentration is less as compared to the concentration of OH− ions that makes the solution basic.

Question 13: Under what soil condition do you think a farmer would treat the soil of his fields with quick lime (calcium oxide) or slaked lime (calcium hydroxide) or chalk (calcium carbonate) ?

Answer: If the soil is acidic and improper for cultivation, then to increase the basicity of soil, the

farmer would treat the soil with quick lime or slaked lime or chalk.

Question 14: What is the common name of the compound CaOCl2 ?

Answer: The common name of the compound CaOCl2 is bleaching powder.

Question 15: Name the substance which on treatment with chlorine yields bleaching powder?

Answer: Calcium hydroxide [Ca (OH)2], on treatment with chlorine, yields bleaching powder.

Question 16: Name the sodium compound which is used for softening hard water.

Answer: Washing soda (Na2CO3.10H2O) is used for softening hard water.

Question 17:- What will happen if a solution of sodium hydrocarbonate is heated? Give the

equation of the reaction involved.

Answer: When a solution of sodium hydrocarbonate (sodium hydrogencarbonate) is heated,

sodium carbonate and water are formed with the evolution of carbon dioxide gas.

Question 18: Write an equation to show the reaction between Plaster of Paris and water.

Answer: The chemical equation for the reaction of Plaster of Paris and water can be represented as

Question 19: A solution turns red litmus blue, its pH is likely to be

(a) 1 (b) 4 (c) 5 (d) 10

Answer: (d) Bases turn red litmus blue and acids turn blue litmus red. Basic solution has a pH value more than 7. Since the solution turns red litmus blue, its pH is likely to be 10.

Question 20: A solution reacts with crushed egg-shells to give a gas that turns lime-water milky.

The solution contains

(a) NaCl (b) HCl (c) LiCl (d) KCl

Answer: (b) The solution contains HCl.

Question 21: 10 mL of a solution of NaOH is found to be completely neutralised by 8 mL 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) 16 mL

Answer: (d) 16 mL of HCl solution will be required.

Question 22: Which one of the following types of medicines is used for treating indigestion?

(a) Antibiotic

(b) Analgesic

(c) Antacid

(d) Antiseptic

Answer: (c) Antacid is used for treating indigestion.

Question 23: Write word equations and then balanced equations for the reaction 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 filings.

Ansewr: (a) Sulphuric acid + Zinc → Zinc sulphate + Hydrogen

(b) Hydrochloric acid + Magnesium → Magnesium chloride + Hydrogen

(c) Sulphuric acid + Aluminium → Aluminium sulphate + Hydrogen

   

(d) Hydrochloric acid + Iron → Ferric chloride + Hydrogen

Question 24: Compounds such as alcohols and glucose also contain hydrogen but are not categorized as acids. Describe an activity to prove it.

Answer: Two nails are fitted on a cork and are kept it in a 100 mL beaker. The nails are then connected to the two terminals of a 6-volt battery through a bulb and a switch. Some dilute HCl is poured in the beaker and the current is switched on. The same experiment is then performed with glucose solution and alcohol solution.

Observations: It will be observed that the bulb glows in the HCl solution and does not glow in the glucose solution.

Result: HCl dissociates into H+ and Cl− ions. These ions conduct electricity in the solution resulting in

the glowing of the bulb. On the other hand, the glucose solution does not dissociate into ions. Therefore , it does not conduct electricity.

Conclusion: From this activity, it can be concluded that all acids contain hydrogen but not all compounds containing hydrogen are acids. That is why, though alcohols and glucose contain hydrogen, they are not categorised as acids.

Question 25: Why does distilled water not conduct electricity, whereas rain water does?

Answer: Distilled water is a pure form of water and is devoid of any ionic species. Therefore, it does not conduct electricity. Rain water, being an impure form of water, contains many ionic species such as acids and therefore it conducts electricity.

Question 26: Why do acids not show acidic behaviour in the absence of water? 

Answer : Acids do not show acidic behaviour in the absence of water because the dissociation of hydrogen ions from an acid occurs in the presence of water only. It is the hydrogen ions that are responsible for the acidic behaviour.

Question 27: Five solutions A, B, C, D and E when tested with universal indicator showed pH as 4, 1, 11, 7 and 9, respectively. Which solution is (a) neutral?

(b) strongly alkaline?

(c) strongly acidic?

(d) weakly acidic?

(e) weakly alkaline?

Answer: Arrange the pH in increasing order of hydrogen-ion concentration.

(a) Neutral → Solution D with pH 7

(b) Strongly alkaline → Solution C with pH 11

(c) Strongly acidic → Solution B with pH 1

(d) Weakly acidic → Solution A with pH 4

(e) Weakly alkaline → Solution E with pH 9

The pH can be arranged in the increasing order of the concentration of hydrogen ions as: 11 < 9 <

7 < 4 < 1

Question 28: Equal lengths of magnesium ribbons are taken in test tubes A and B. Hydrochloric

acid (HCl) is added to test tube A, while acetic acid (CH3COOH) is added to test tube B. In which

test tube will the fizzing occur more vigorously and why?

Answer: The fizzing will occur strongly in test tube A, in which hydrochloric acid (HCl) is added.

This is because HCl is a stronger acid than CH3COOH and therefore produces hydrogen gas at a

faster speed due to which fizzing occurs.

Question 29: Fresh milk has a pH of 6. How do you think the pH will change as it turns into curd? Explain your answer.

Answer: The pH of milk is 6. As it changes to curd, the pH will reduce because curd is acidic in

nature. The acids present in it decrease the pH.

Question 30: 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?

Answer: (a) The milkman shifts the pH of the fresh milk from 6 to slightly alkaline because in

alkaline condition, milk does not set as curd easily.

(b) Since this milk is slightly basic than usual milk, acids produced to set the curd are neutralized

by the base. Therefore, it takes a longer time for the curd to set.

Question 31: Plaster of Paris should be stored in a moisture-proof container. Explain why?

Answer: Plaster of Paris (POP) should be stored in a moisture-proof container because Plaster of

Paris, a powdery mass, absorbs water (moisture) to form a hard solid known as gypsum.

Question 32: What is a neutralization reaction? Give two examples.

Answer: A reaction in which an acid and base react with each other to give a salt and water is

termed as neutralization reaction. In this reaction, energy is evolved in the form of heat.

For example:

(i)  

(ii) During indigestion (caused due to the production of excess of hydrochloric acid in the stomach), we administer an antacid (generally milk of magnesia, Mg(OH)2 which is basic in nature). The antacid neutralizes the excess of acids and thus gives relief from indigestion.

Mg(OH)2  + 2HCl  --------->  MgCl2  +   2H2O

Question 33: Give two important uses of washing soda and baking soda.

Answer: Two important used of washing soda and baking soda are as follows:

(1) Washing soda:

(a) It is used in glass, soap, and paper industries.

(b) It is used to remove permanent hardness of water.

(2) Baking soda:

(a) It is used as baking powder. Baking powder is a mixture of baking soda and a mild acid known as tartaric acid. When it is heated or mixed in water, it releases CO2 that makes bread or cake fluffy.

(b) It is used in soda-acid fire extinguishers.