Life Processes

Life Processes

Life Processes:10 Class NCERT Q/A

Life Processes all Problem answer

Problem 1: Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?

Answer: Multicellular organisms such as humans possess complex body designs. They have specialized cells and tissues for performing various necessary functions of the body such as the intake of food and oxygen. Unlike unicellular organisms, multicellular cells are not in direct contact with the outside environment. Therefore, diffusion cannot meet their oxygen requirements.

 Problem 2: What criteria do we use to decide whether something is alive?

Answer: Any visible movement such as walking, breathing, or growing is generally used to decide whether something is alive or not. However, a living organism can also have movements, which are not visible to the naked eye. Therefore, the presence of life processes is a fundamental criterion that can be used to decide whether something is alive or not.

Problem 3: What is outside raw materials used by an organism?

Answer: An organism uses outside raw materials mostly in the form of food and oxygen. The raw materials required by an organism can be quite varied depending on the complexity of the organism and its environment.

Problem 4: What processes would you consider essential for maintaining life?

Answer: Life processes such as nutrition, respiration, transportation, excretion, etc. are essential for maintaining life.

 Problem 5: What are the differences between autotrophic nutrition and heterotrophic nutrition?

Answer:

Autotrophic nutrition	Heterotrophic nutrition
(i) Food is synthesized from simple inorganic raw materials such as CO2and water.	(i) Food is obtained directly or indirectly from autotrophs. This food is broken down with the help of enzymes.
(ii) Presence of green pigment (chlorophyll) is necessary.	(ii) No pigment is required in this type of nutrition.
(iii)Food is generally prepared during the daytime.	(iii)Food can be prepared at all times.

 (iv)All green plants and some bacteria have          (iv)All animals and fungi have this type of this type of nutrition.                                                                 nutrition.

 Problem 6: Where do plants get each of the raw materials required for photosynthesis?

Answer: The following raw materials are required for photosynthesis:

• The raw material CO2 enters from the atmosphere through stomata.

• Water is absorbed from the soil by the plant roots.

• Sunlight, an important component to manufacture food, is absorbed by the chlorophyll and other green parts of the plants.

Problem 7: What is the role of the acid in our stomach?

Answer: The hydrochloric acid present in our stomach dissolves bits of food and creates an acidic medium. In this acidic medium, enzyme pepsinogen is converted to pepsin, which is a protein-digesting enzyme.

Problem 8: What is the function of digestive enzymes?

Answer: Digestive enzymes such as amylase, lipase, pepsin, trypsin, etc. help in the breaking down of complex food particles into simple ones. These simple particles can be easily absorbed by the blood and thus transported to all the cells of the body.

Problem 9: How is the small intestine designed to absorb digested food?

Answer: The small intestine has millions of tiny finger-like projections called villi These villi increase the surface area for more efficient food absorption. Within these villi, many blood vessels are present that absorb the digested food and carry it to the bloodstream. From the bloodstream, the absorbed food is delivered to each and every cell of the body.

The enlarged view of a villus

Problem 10: What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?

Answer: Terrestrial organisms take up oxygen from the atmosphere whereas aquatic animals need to utilize oxygen present in the water. Air contains more O2 as compared to water. Since the content of O2 in the air is high, the terrestrial animals do not have to breathe faster to get more oxygen. Therefore, unlike aquatic animals, terrestrial animals do not have to show various adaptations for better gaseous exchange.

Problem 11: What are the different ways in which glucose is oxidized to provide energy for various organisms?

Answer: Glucose is first broken down in the cell cytoplasm into a three carbon molecule called pyruvate. Pyruvate is further broken down by different ways to provide energy. The breakdown of glucose by different pathways can be illustrated as follows.

In yeast and human muscle cells, the breakdown of pyruvate occurs in the absence of oxygen whereas, in mitochondria, the breakdown of pyruvate occurs in the presence of oxygen.

Problem 12: How is oxygen and carbon dioxide transported in human beings?

Answer: Haemoglobin transports oxygen molecule to all the body cells for cellular respiration. The hemoglobin pigment present in the blood gets attached to four O2 molecules that are obtained from breathing. It thus forms oxyhemoglobin and the blood becomes oxygenated. This oxygenated blood is then distributed to all the body cells by the heart. After giving away O2 to the body cells, blood takes away CO2 which is the end product of cellular respiration. Now the blood becomes de-oxygenated.

Since hemoglobin pigment has less affinity for CO2, CO2 is mainly transported in the dissolved form. This de-oxygenated blood gives CO2 to lung alveoli and takes O2 in return.

Transportation of O2 and CO2 in blood

Problem 13: How are the lungs designed in human beings to maximize the area for exchange of gases?

Answer: The exchange of gases takes place between the blood of the capillaries that surround the alveoli and the gases present in the alveoli. Thus, alveoli are the site for exchange of gases. The lungs get filled up with air during the process of inhalation as ribs are lifted up and the diaphragm is flattened. The air that is rushed inside the lungs fills the numerous alveoli present in the lungs.

Each lung contains 300-350 million alveoli. These numerous alveoli increase the surface area for gaseous exchange making the process of respiration more efficient.

Problem 14: What are the components of the transport system in human beings? What are the functions of these components?

Answer: The main components of the transport system in human beings are the heart, blood, and blood vessels.

The heart pumps oxygenated blood throughout the body. It receives deoxygenated blood from the various body parts and sends this impure blood to the lungs for oxygenation.

Being a fluid connective tissue, blood helps in the transport of oxygen, nutrients, CO2, and nitrogenous wastes.

The blood vessels (arteries, veins, and capillaries) carry blood either away from the heart to various organs or from various organs back to the heart.

Problem 15: Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?

Answer: Warm-blooded animals such as birds and mammals maintain a constant body temperature by cooling themselves when they are in a hotter environment and by warming their bodies when they are in a cooler environment. Hence, these animals require more oxygen (O2) for more cellular respiration so that they can produce more energy to maintain their body temperature.

Thus, it is necessary for them to separate oxygenated and de-oxygenated blood, so that their circulatory system is more efficient and can maintain their constant body temperature.

Problem 16: What are the components of the transport system in highly organized plants?

Answer: In highly organized plants, there are two different types of conducting tissues − xylem and phloem. Xylem conducts water and minerals obtained from the soil (via roots) to the rest of the plant. Phloem transports food materials from the leaves to different parts of the plant body.

Problem 17: How are water and minerals transported in plants?

Answer: The components of xylem tissue (tracheids and vessels) of roots, stems, and leaves are interconnected to form a continuous system of water-conducting channels that reaches all parts of the plant. Transpiration creates a suction pressure, as a result of which water is forced into the xylem cells of the roots. Then there is a steady movement of water from the root xylem to all the plant parts through the interconnected water-conducting channels.

Components of xylem tissue 

Problem 18: How is the food transported in plants?

Phloem transports food materials from the leaves to different parts of the plant body. The transportation of food in phloem is achieved by utilizing energy from ATP. As a result of this, the osmotic pressure in the tissue increases causing water to move into it. This pressure moves the material in the phloem to the tissues which have less pressure. This is helpful in moving materials according to the needs of the plant. For example, the food material, such as sucrose, is transported into the phloem tissue using ATP energy.

Components of phloem tissue

Problem 19: Describe the structure and functioning of nephrons.

Answer: Nephrons are the basic filtering units of kidneys. Each kidney possesses a large number of nephrons, approximately 1-1.5 million. The main components of the nephron are glomerulus, Bowman’s capsule, and along renal tubule.

Structure of a nephron

Functioning of a nephron:

The blood enters the kidney through the renal artery, which branches into many capillaries associated with glomerulus.

The water and solute are transferred to the nephron at Bowman’s capsule. In the proximal tubule, some substances such as amino acids, glucose, and salts are selectively reabsorbed and unwanted molecules are added in the urine.

The filtrate then moves down into the loop of Henle, where more water is absorbed.

From here, the filtrate moves upwards into the distal tubule and finally to the collecting duct.

Collecting duct collects urine from many nephrons.

The urine formed in each kidney enters a long tube called ureter. From ureter, it gets transported to the urinary bladder and then into the urethra.

Problem 20: What are the methods used by plants to get rid of excretory products?

Answer: Plants can get rid of the excess of water by transpiration. Waste materials may be stored in the cell vacuoles or as gum and resin, especially in old xylem. It is also stored in the leaves that later fall off.

Problem 21: How is the amount of urine produced regulated?

Answer: The amount of urine produced depends on the amount of excess water and dissolved wastes present in the body. Some other factors such as habitat of an organism and hormone such as Anti-diuretic hormone (ADH) also regulates the amount of urine produced.

Problem 22: The kidneys in human beings are a part of the system for

(a) nutrition.

(b) respiration.

(c) excretion.

(d) transportation.

(c) In human beings, the kidneys are a part of the system for excretion.

Problem 24: The autotrophic mode of nutrition requires

(a) carbon dioxide and water.

(b) chlorophyll.

(c) sunlight.

(d) all of the above.

Answer: (d) The autotrophic mode of nutrition requires carbon dioxide, water, chlorophyll, and sunlight.

Problem 23: The xylem in plants are responsible for

(a) transport of water.

(b) transport of food.

(c) transport of amino acids.

(d) transport of oxygen.

(a)    In a plant, the xylem is responsible for transport of water.

Problem 25: The breakdown of pyruvate to give carbon dioxide, water and energy takes place in

(a) cytoplasm.

(b) mitochondria.

(c) chloroplast.

(d) nucleus.

Answer: (b) The breakdown of pyruvate to give carbon dioxide, water and energy takes place in mitochondria.

Problem 26: How are fats digested in our bodies? Where does this process take place?

Answer: Fats are present in the form of large globules in the small intestine. The small intestine gets the secretions in the form of bile juice and pancreatic juice respectively from the liver and the pancreas. The bile salts (from the liver) break down the large fat globules into smaller globules so that the pancreatic enzymes can easily act on them. This is referred to as emulsification of fats. It takes place in the small intestine.

Problem 27: What are the necessary conditions for autotrophic nutrition and what are its by-products?

Answer: Autotrophic nutrition takes place through the process of photosynthesis. Carbon dioxide, water, chlorophyll pigment, and sunlight are the necessary conditions required for autotrophic nutrition. Carbohydrates (food) and O2 are the by-products of photosynthesis.

Problem 28: What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.

Answer:

Aerobic respiration	Anaerobic respiration
1. It occurs in the presence of O2.	1. It occurs in the absence of O2.
2. It involves the exchange of gases between the organism and the outside environment.	2. Exchange of gases is absent.
3. It occurs in the cytoplasm and mitochondria.	3. It occurs only in the cytoplasm.
4. It always releases CO2 and H2O.	4. End products vary.
5. It yields 36 ATPs.	5. It yields only 2 ATPs.

Anaerobic respiration occurs in the roots of some waterlogged plants, some parasitic worms, animal muscles, and some micro-organisms such as yeasts.

Problem 29: How are the alveoli designed to maximize the exchange of gases?

Answer: The alveoli are the small balloon-like structures present in the lungs. The walls of the alveoli consist of the extensive network of blood vessels. Each lung contains 300−350 million alveoli, making it a total of approximately 700 million in both the lungs. The alveolar surface when spread out covers about 80 m2area. This large surface area makes the gaseous exchange more efficient.

Alveoli and capillaries

Problem 30: What would be the consequences of a deficiency of hemoglobin in our bodies?

Answer: Haemoglobin is the respiratory pigment that transports oxygen to the body cells for cellular respiration. Therefore, deficiency of hemoglobin in the blood can affect the oxygen supplying capacity of blood. This can lead to the deficiency of oxygen in the body cells. It can also lead to a disease called anemia.

Problem 31: Describe double circulation in human beings. Why is it necessary?

Answer: The human heart is divided into four chambers − the right atrium, the right ventricle, the left atrium, and the left ventricle.

The flow of blood in the heart:

The heart has superior and inferior vena cava, which carries de-oxygenated blood from the upper and lower regions of the body respectively and supplies this de-oxygenated blood to the right atrium of the heart.

The flow of blood in the human heart

The right atrium then contracts and passes the de-oxygenated blood to the right ventricle, through an auriculo-ventricular aperture.

Then the right ventricle contracts and passes the de-oxygenated blood into the two pulmonary arteries, which pumps it to the lungs where the blood becomes oxygenated. From the lungs, the pulmonary veins transport the oxygenated blood to the left atrium of the heart. Then the left atrium contracts and through the auriculo-ventricular aperture, the oxygenated blood enters the left ventricle.

The blood passes to aorta from the left ventricle. The aorta gives rise to many arteries that distribute the oxygenated blood to all the regions of the body.

Schematic diagram of blood circulation in humans

Therefore, the blood goes twice through the heart. This is known as double circulation.

Importance of double circulation:

The separation of oxygenated and de-oxygenated blood allows a more efficient supply of oxygen to the body cells. This efficient system of oxygen supply is very useful in warm-blooded animals such as human beings.

As we know, warm-blooded animals have to maintain a constant body temperature by cooling themselves when they are in a hotter environment and by warming their bodies when they are in a cooler environment. Hence, they require more O2 for more respiration so that they can produce more energy to maintain their body temperature. Thus, the circulatory system of humans is more efficient because of the double circulatory heart.

Problem 32: What are the differences between the transport of materials in xylem and phloem? Answer:

Transport of materials in xylem	Transport of materials in phloem
(i) Xylem tissue helps in the transport of water and minerals.	(i) Phloem tissue helps in the transport of food.
(ii)Water is transported upwards from roots to all other plant parts.	(ii)Food is transported in both upward and downward directions.
(iii)Transport in xylem occurs with the help of simple physical forces such as transpiration pull.	(iii)Transport of food in phloem requires energy in the form of ATP.

by ARUN KUMAR with the help of ncert

some important Problem answer

Acids, Bases, and Salts

Acids, Bases, and Salts

Problem 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?

Solution:- If the color of the red litmus paper gets changed to blue, then it is a base and if there is no color change, then it is either acidic or neutral. Thus, a 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 color to blue, then it is basic. Therefore, out of the three, one is eliminated. Out of the remaining two, anyone 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 color of red litmus turns blue, then the second solution is neutral and if there is no change in color, then the second solution is acidic. This is because acidic and basic solutions neutralize each other.

Hence, we can distinguish between the three types of solutions.

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

Solutions:- 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.

Problem 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?

Solution:- Hydrogen gas is usually liberated when an acid reacts with a metal. Take a 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.

Problem 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.

Solutions:-

Problem 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?                                     

Solutions:- 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:

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

Problem 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.

Problem 7: Why does dry HCl gas not change the color 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 color 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 a large amount of heat generated, the mixture splashes out and causes burns.

Problem 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.

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

dissolved in a solution of sodium hydroxide?

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

dissolved in a solution of sodium hydroxide.

Problem 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?

Solutions:- 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.

Problem 11: What effect does the concentration of ions have on the nature of the solution?

Answer: Concentration 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.

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

Answer: Yes, the basic solution also has ions. However, their concentration is less as

compared to the concentration of OH− ions that makes the solution basic.

Problem 13: Under what soil condition 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)?

Answer: If the soil is acidic and improper for cultivation, then to increase the basicity of soil, the farmer would treat the soil with quicklime or slaked lime or chalk.

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

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

Problem 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

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

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

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

equation of the reaction involved.

Answer: When a solution of sodium hydrocarbonate (sodium hydrogen carbonate) is heated, sodium carbonate and water are formed with the evolution of carbon dioxide gas.

Problem 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

Problem 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. The basic solution has a pH value of more than 7. Since the solution turns red litmus blue, its pH is likely to be 10.

Problem 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.

Problem 21: 10 mL of a solution of NaOH is found to be completely neutralized 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.

Problem 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.

Problem 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 aluminum powder.

(d) dilute hydrochloric acid reacts with iron filings.

Answer: (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

Problem 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 into the beaker and the current is switched on. The same experiment is then performed with a glucose solution and an alcohol solution.

Observations:

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

                                        

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 categorized as acids.

Problem 25: Why does distilled water not conduct electricity, whereas rainwater does?

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

Problem 26: Why do acids not show acidic behavior in the absence of water?

Acids do not show acidic behavior 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 behavior.

Problem 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

Problem 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.

Problem 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.

Problem 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.

Problem 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.

Problem 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 a neutralization reaction. In this reaction, energy is evolved in the form of heat.

For example:

Problem 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 the permanent hardness of water.

(2) Baking soda:

(a) It is used as the 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.

                                                             {written by=ARUN KUMAR}

                                                             With the help of ncert solution on LM

                                             ( important ncert solution)