x Ch.1 Chemical reactions and equations key consents
1. Chemical reaction: A chemical reaction involves a chemical change in which substances react to form new substances with entirely new properties. Substances that react or take part in the reaction are known as reactants and the substances formed are known as products.
2. Physical change: If a change involves change in colour or state but no new substance is formed, then it is a physical change.
3. Chemical change: If a change involves formation of new substances, it is a chemicalchange.
4. Chemical equation: The symbolic representation of a chemical reaction is called a chemicalequation.
5. Exothermic and endothermic reactions: If heat is evolved during a reaction, then such a reaction is known as exothermic reaction. If heat is absorbed from the surroundings, then such a reaction is known as endothermic reaction
6. Combination reaction: Combination reaction is a reaction in which two or more substances combine to give a single product.
7. Decomposition reaction: In a decomposition reaction, a single reactant decomposes to give 2 or more products. Decomposition reactions require energy in the form of heat, light or electricity
8. Displacement reaction: A reaction in which a more active element displaces less active element from its salt solution.
9. Reactivity series: The Reactivity series is a list of metals arranged in the order of decreasing reactivity. The most reactive metal is placed at the top and the least reactive metal is placed at the bottom.
10.Double displacement reaction: A chemical reaction in which there is an exchange of ions between the reactants to give new substances is called a double displacement reaction.
11.Precipitation reaction: An insoluble solid known as precipitate is formed during a double is placement reaction. Such reactions are also known as precipitation reactions.
12.Redox reaction: A reaction, in which oxidation and reduction takes place simultaneously is known as redox reaction.
13.Oxidation: Oxidation is a chemical process in which a substance gains oxygen or loses hydrogen.
14.Reduction: Reduction is a chemical process in which a substance gains hydrogen or loses oxygen.
15.During a chemical reaction, there is a breaking of bonds between atoms of the reacting molecules to give products.
16. A chemical reaction can be observed with the help of any of the following observations:
a) Evolution of a gas b) Change in temperature
c) Formation of a precipitate d) Change in colour e) Change of state
17. Skeletal chemical equation: A chemical equation which simply represents the symbols and formulae of reactants and products taking part in the reaction is known as skeletalchemical equation
for a reaction. For example: For the burning of Magnesium in the air, Mg + O2 → MgO is the skeletal equation.
18. Balanced chemical equation: A balanced equation is a chemical equation in which number of atoms of each element is equal on both sides of the equation i.e. number of atoms of an element on
reactant side = number of atoms of that element on the product side.
19. As per the law of conservation of mass, the total mass of the elements present in the products of a chemical reaction is equal to the total mass of the elements present in the reactants.
20. Decomposition reaction: In a decomposition reaction, a single reactant decomposes to give 2 or more products. Decomposition reactions require energy in the form of heat, light or electricity
Types of decomposition reactions:
a. Decomposition reactions which require heat are known as thermolytic decomposition reactions
b. Decomposition reactions which require light are known as photolytic decomposition reactions
c. Decomposition reactions which require electricity are known as electrolytic decomposition reactions
1-mark Questions/ Answers
1. What happens when magnesium ribbon burns in air?
Ans. When magnesium ribbon burns in air, it combines with the oxygen to form magnesium oxide.
2Mg(s) + O2(g) ® 2MgO(s)
2. Name the gas evolved when zinc reacts with dil. HCl.
Ans. Hydrogen gas is evolved.
3. What is a chemical equation?
Ans. A chemical equation is a symbolic notation that uses formulae instead of words to represent a chemical equation.
4. On what chemical law, balancing of chemical equation is based?
Ans. Balancing of a chemical equation is based on the law of conservation of mass.
5. Represent decomposition of ferrous sulphate with the help of balanced chemical equation.
Ans. 2FeSO4(s) ® Fe2O3(s) + SO2(g) + SO3(g)
6. When carbon dioxide is passed through lime water, it turns milky, why?
Ans. Lime water (calcium hydroxide) combines with carbon dioxide to form a suspension of calcium carbonate which makes lime water milky. Ca(OH)2 + CO2 ® CaCO3 + H2O
7. A zinc rod is left for nearly 20 minutes in a copper sulphate solution. What change would you observe in zinc rod?
Ans. Zinc rod will change into zinc sulphate.
8. What type of reaction is this: Na2SO4 + BaCl2 ® BaSO4 + 2NaCl
Ans. It is a double displacement reaction.
9. Identify the compound oxidized in the following reaction. H2S (g) + Cl2 ® S(s) + 2HCl (g)
Ans. H2S is oxidized.
10. What is rust? Ans. Rust is mainly hydrated iron (III) oxide, Fe2O3.xH2O.
11. How does the food become rancid?
Ans. Food becomes rancid when fat and oils present in the food are oxidized.
2-marks Questions/ Answers
Q.1. An iron knife kept dipped in a blue copper sulphate solution turns the blue solution light green. Why?
Ans. As we know iron is more reactive than copper. So, it displaces Cu from CuSO4 solution and forms ferrous sulphate which is of Light Green Colour.
CuSO4 (aq) + Fe (s) → FeSO4(aq) + Cu(s)
Blue colour light green colour
Q.2. A copper coin is kept in a solution of silver nitrate for some time. What will happen to the coin and the colour of the solution?
Ans. We know that copper is more reactive than silver, so it will displace silver from its salt solution:
Cu(s) + 2AgNO3(aq) → Cu(NO3)2(aq) + 2Ag(s)
So the solution will turn blue due to the formation of copper nitrate.
Q.3. What do you understand by precipitation reaction? Explain with suitable examples.
Ans. Precipitate. When two reactants react and product formed remains insoluble and settles as a solid it is called a precipitate. Such reactions in which precipitate is formed are called precipitation reactions. For example,(i) when aqueous solution of sodium sulphate is mixed with the aqueous solution or barium chloride, barium sulphate comes in the form of white precipitate
Na2SO4(aq) + BaCl2(aq) → BaSO4(↓) + 2NaCl(aq)
(ii) When aqueous solution of sodium chloride is mixed with the aqueous solution of silver nitrate, silver chloride comes in the form of white precipitate.
Q.4. What is lime-water test for the detection of carbon dioxide?
Ans. When carbon dioxide gas is passed through lime water ,it turns milky due to the formation of milky suspension (precipitate) of calcium carbonate. Carbon dioxide is produced by the action of dilute HCl on sodium carbonate.
Na2CO3(s) + 2HCl(aq) → 2NaCl + H2O(l) + CO2
Carbon dioxide gas produced in this reaction is passed through lime water that changes to milky colour due to the formation of calcium carbonate.
Ca(OH)2(aq) + CO2(g) → Caco3 + CO2(g)
3 Marks Questions/ Answers
Q.5. What is corrosion? State the conditions necessary for rusting of iron. How rusting is harmful?
Ans: Corrosion. The process of eating away of the metal by the action of atmospheric reagents changing the metal into its compound is called corrosion.
Rusting of Iron. When iron and iron objects are exposed to atmosphere, they are attacked by air and moisture (water) of the atmosphere and a brown and orange coloured layer is formed on the surface. It is called rust which is mainly hydrated iron (iii) oxide Fe2O3.xH2O.
Harmful Effect of Rusting. Hydrated iron (iii) oxide is brittle substance and moves away from the surface thus the object is damaged. The objects get holes, cavities and rough surface.
Conditions necessary for rusting :
(i) Open surfaces of the metal. (ii) Presence of air (Oxygen). (iii) Presence of moisture (water).
Q.6. What is rancidity? Write the common method to prevent it.
Ans. When food item are kept unprotected for some time, they give some unpleasant smell and taste and become rancid. This process is called rancidity. Actually, the micro organisms oxidise the fat and oils present in them. So oxidation of food items need to be prevented to protect them.
Common methods to Prevent Rancidity of Food item:
(i) Keeping the food at low temperature (ii) Keeping food item in air tight containers
(iii) By filling nitrogen in the food storage bags.
5 Marks Questions/ Answers
1. a. Why cannot a chemical change be normally reversed?
b. why is it always essential to balance a chemical equation?
c. what happens when CO2 gas is passed through lime water and why does it disappear on passing excess CO2?
d. Can rusting of iron takes place in distilled water?
Ans: a. In a chemical change some bonds are broken and some bonds are formed. The products are quite different from the reactants. Therefore it normally can’t be reversed.
b. A chemical equation has to be balanced to satisfy the law of conservation of mass.
c. On passing CO2 gas through lime water, it turns milky due to formation of insoluble calcium carbonate which dissolves on passing excess CO2 due to formation of soluble calcium bicarbonate.
Ca(OH)2 + CO2(g) --------------→ CaCO3(s) + H2O(l)
CaCO3(s) + H2O(l) + CO2 (g) ---------------→ Ca(HCO3)2(soluble)
d. No, rusting of iron cannot take place in distilled water because it neither contains dissolved oxygen nor CO2 both are essential for rusting of iron.
Hots Questions
Q 1 . The marble statues often slowly get corroded when kept in open for a long time .Assign a suitable explanation
Ans-SO2,NO2 gases are released into the atmosphere from various sources. These dissolve in rain water to give acid which corrodes marble statues
2SO2+O2 --------------→ 2SO3
H2O+SO3 --------------→ H2SO4
2NO2+H2O 2HNO3 CaCO3+H2SO4--------------→ CaSO 4 +H2O+CO2
CaCO3+2HNO3 --------------→Ca(NO3)2+H2O+CO2
Q 2. You are given the following materials
(1) marble chips (2)dilute hydrochloric acid (3)Zinc granules ,identify the type of reaction when marble chips and Zinc granules are added separately to acid taken in two test tubes
Ans-(i) marble chips react with dilute hydrochloric acid to form calcium chloride and carbon dioxide .it is a double displacement reaction
CaCO3+2HCl → CaCl2 + H2O +CO2
(ii)Zinc granules react with dilute hydrochloric acid to give hydrogen gas. it is a displacement reaction
Zn(s)+2HCl → ZnCl2(aq)+H2(g)
Q3. The gases hydrogen & chlorine do not react with each other even if kept together for a long time . However , in the presence of sunlight , they readily combine . What does actually happen ?
Ans-In Chemical reactions , energy is needed to break the bonds present in the reacting molecules so that they may combine to form the products . In this reaction , sunlight is the source of energy in the form of photons . The energy made available by sunlight helps in breaking the bonds & this leads to chemical reaction between hydrogen & chlorine.
H2 (g) + Cl2(g) sunlight→ 2HCl (g)
Q 4. A,B&C are three elements which undergo chemical reactions in the following way
A2O3 + 2B®B2O3 + 2A 3CSO4 + 2B -® B2(SO4)3 + 3C 3CO+ 2A ®A2O3 +3C
Answer the following
(A) Which element is most reactive ? (B) Which element is least reactive ?
Ans: a) The most reactive element is ‘B’. It has displaced both ‘A’ and ‘c’ from their compounds.
b) The least reactive element is ‘C’ as it has been displaced by both ‘A’ and ‘B’ .
Q. A water insoluble substance ‗X‘ on reacting with dilute H2SO4 released a colourless and odourless gas accompanied by brisk effervescence. When the gas was passed through water , the solution obtained turn blue litmus red . On bubbling the gas through lime water , it initially became milky and the milkiness disappeared when the gas was passed in excess . Identify the substance ‗X‘ and write the chemical equations of the reaction involved
ANS: the water insoluble substance ‘X’ is most probably metal carbonate ( CaCO3 ). The chemical reaction that involved are given below
CaCO3 (s) + H2SO4 (aq) →CaSO4 ( aq) + H2O (aq) + CO2 (g)
Ca(OH)2 (s) + CO2 (g) → CaCO3 (s) ( milky) + H2O (l)
CaCO3 (s) + CO2 (g) + H2O (aq) →Ca(HCO3)2 ( milkiness)
Extra score questions:
Q 1. If you collect silver coins and copper coins. After some day a black coating on silver coins and a green coating on copper coins. Which chemical phenomenon is responsible for these coatings? Write the chemical name of black and green coatings
Ans: Corrosion is responsible for this coating. Black coating is due to formation of Ag2S and green coating is due to formation of CuCO3.Cu (OH)2
Q.2. An aqueous solution of metal nitrate P reacts with sodium bromide solution to form yellow ppt of compound Q which is used in photography. Q on exposure to sunlight undergoes decomposition reaction to form metal present in P along with reddish brown gas. Identify P&Q . Write the chemical reaction & type of chemical reaction.
Ans: P = Ag NO3 , Q = AgBr 2 A gBr (s) ® 2Ag(s) + B r2(g) Photochemical decomposition
Q.3. A substance X used for coating iron articles is added to a blue solution of a reddish brown metal Y, the color of the solution gets discharged Identify X and Y & also the type of reaction.
Ans. 6 X= Fe, Y = Cu, Displacement reaction.
Q.4. A student burnt a metal A found in the form of ribbon. The ribbon burnt with a dazzling flame & a white powder B is formed which is basic in nature. Identify A &B. Write the balanced chemical equation.
Ans.11 X = Mg, Y = MgO, Mg + O2® 2 MgO
Q.5. why magnesium ribbon cleaned before burning?
Ans: The magnesium ribbon is always found with a white layer of MgO due attack of moist air. So, magnesium ribbon cleaned before burning.
Q.6. During electrolysis of water gas collected in one test tube is double than other why?
Ans: On electrolysis weter decompose into hydrogen and oxygen in ratio 2:1 by volume so,H2 gas collected in one test tube is double than O2
Life Process
Q1. Define the following terms:
1) nutrition
2) photosynthesis
3) peristalsis
4) excretion
5) osmoregulation
6) holozoic nutrition
Ans. 1) 1 Nutrition-It is the mode of taking food by an organism and its utilization by
the body.
2)Photosynthesis-It is the process by which green plants can prepare their own
food in the presence of sunlight,carbondioxide,water,minerals and chlorophyll.
3)peristalsis:-it is a wave of contraction and expansion that takes place in the
Alimentary canal. It pushes the food forward.
4)excretion:-the process of elimination of metabolic waste from the body.
5) osmoregulation :-regulating the amount of water and salts in the body.
6)holozoic nutrition:-it is the mode of heterotrophic nutrition that involves
The intake of solid food.
Q2.Distinguish between:
1) breathing and respiration
Breathing respiration
It’s a physical process It’s a biochemical process
It consumes energy It releases energy
Its taking in fresh air and giving out foul air It’s the oxidation of respiratory substrate
2) parasite and saprophyte
Parasite
Saprophyte
Obtains nutrition from a living organism
called host
Obtains nutrition from organic remains
Possess sucking organs They are absent
3) aerobic and anaerobic respiration
Aerobic
Anaerobic respiration
It requires oxygen It doesn’t require oxygen
Releases 38 ATP molecules Releases only 2 ATP molecules
Food is completely broken down Food is incompletely broken down
4) inhalation and exhalation
Inhalation Taking in fresh air Giving out foul air Diaphragm becomes flat Diaphragm becomes dome shaped Air pressure decreases in the lungs Air pressure increases in the lungs
Inhalation Taking in fresh air Giving out foul air Diaphragm becomes flat Diaphragm becomes dome shaped Air pressure decreases in the lungs Air pressure increases in the lungs
5) ingestion and egestion
Ingestion Egestion
It’s the process of taking in food It’s the process of throwing out faecal
matter out of the body
Involves catching,holding and putting food
‘in the body
Involves piling up of faecal matter and its
elimination thru anus
.
6) plant and animal respiration
Plant respiration Animal respiration
Rate of respiration is slow Rate of respiration is fast
Breathing is absent Present
Respiratory surface absent present
Q3. How do plants get rid of their waste products?
Ans. Plants get rid of their waste products by:
1) waste products are stored in old leaves that soon fall off.
2) Bark consists of dead cells which is peeled off periodically.
3) Some waste substances are excreted by roots.
4) Resins, gums , tannins etc are stored in old xylem.
Q4. How does amoeba dispose off its waste products?
Ans. amoeba lacks excretory organs. Waste products like ammonia and CO2 are passed outside through the process of diffusion. Contractile vacuole also plays an important role in
he process of excretion.
Q5. Describe the mechanism of urine formation in humans.
Ans. its completed in 4 steps: a) glomerular filtration: blood flows under pressure inside the glomerulus . as a result, it undergoes ultrafiltration. Urea, uric acid, amino acids, hormones, glucose, ions and water are filtered out and enter the Bowmans capsule. b) Reabsorption:the filtrate passes thru proximal convoluted tubule. The capillaries absorb all the useful components like: glucose, amino acids, ions etc. c) Tubular secretion: it occurs in distal convoluted tubule. It is the active secretion of waste by the blood capillaries into the urinary tubule. It ensures the removal of all the waste from the blood. d) Concentration of urine: 75% of water is reabsorbed in proximal convoluted tubule.some 10% of water reabsorbed in henles loop. e) Ureters : these are the narrow muscular tubesthat carry urine from kidneys to urinary bladder. f) Urinary bladder: it is a pear shaped sac that stores urine. g) Utrethra: it is a tube that takes urine from bladder to outside.
Q6. Why is trachea lined with the rings of cartilage?
Ans. Trachea is lined with the rings of cartilage to prevent it from collapsing.
Q7. Identify the respiratory organ in : a)leech b) cockroach c) crab d)mussel e)tadpole
Ans. a) skin b) trachea/ spiracles c) gills d) gills e) gills
Q8. How do plants exchange gases?
Ans. Plants exchange gases by the process of diffusion. Stomata help in the exchange of gases. CO2 gas is taken in and O2 is released by the process of photosynthesis.
Q9. What is the role of HCL in the stomach.
Ans. it has two roles: 1) kills the microbes that enter along with food. 2) Creates an acidic medium for pepsin functioning.
Q10. Name the raw materials of photosynthesis .
Ans. 4 requirements of photosynthesis are- 1 carbondioxide –is taken through stomata. 2 water and minerals- are transported to the leaves by the vessels. 3 chlorophyll-is present in the leaves of the plants. 4 sunlight-is absorbed by the chlorophyll present in the leaves.
Q11. Identify the specific mode of nutrition in : a) cuscuta b) ascaris c) mushroom d) deer e) humans Ans. a) parasitic b) parasitic c) saprophytic d)and e) holozoic
Q12. What is fermentation? What is its use?
Ans. fermentation is the kind of anaerobic respiration carried out by a unicellular organism called yeast. Yeast converts a sugar solution into alcohol and also releases CO2 Gas during this process. Its used in bakery and brewery industries.
Q13. Mention the raw materials needed for photosynthesis.
Ans. 4 requirements of photosynthesis are- 1 carbondioxide –is taken through stomatas 2 water and minerals- are transported to the leaves by the vessels. 3 chlorophyll-is present in the leaves of the plants. 4 sunlight-is absorbed by the chlorophyll present in the leaves.
Q14. Draw a well labeled diagram of human respiratory system.
. Q15. Draw a well labeled diagram of human excretory system.
. Q16. Draw a well labeled diagram of cross section of a leaf. Q17.
Draw a dig. Of stomata and write its 2 functions
Ans. functions:a) exchange of gases b) loss of extra water by transpiration
Q18. Draw a well labeled diagram of human digestive system
Q19. Name the 5 steps of holozoic nutrition
Ans. 1) ingestion:-- the process of intake of food. 3) digestion:-- changing complex food substances to simple form by the action of enzymes. 4) Absorption:-- digested food is absorbed in blood. 5) Assilmilation:-- the absorbed food components are converted into components of cytoplasm. 6) Egestion :-throwing out of waste.
Q20. Name the secretions and their role in digestion for the following glands::
Ans. Gland Secretion Function Salivary( mouth) Saliva( salivary amylase) Digests carbohydrate( starch) Gastric( stomach) Mucus, HCL, Pepsin Mucus has protective function HCL kills the microbes Pepsin digests proteins. Pancreas(abdomen) Pancreatic juice Trypsin digests proteins Amylase digests carbohydrate Lipase digests lipids and fats. Liver( abdomen) Bile Emulsification of fats
Q21 . why do aquatic organisms show a higher breathing rate?
Ans. this is bcos, water has low O2 content than the content of O2 in air.
Q22. why do we feel muscle cramps after heavy exercise?
Ans. this is bcos our cells and tissues become O2 deficient and start undergoing anaerobic respiration. This produces lactic acid and we feel muscle cramps.
Q23. Why is it advised to breathe thru nose?
Ans. The mucus and hair present in the nasal cavity help to filter the inhaled air.
Q24.What is a diaphragm?
Ans. it’s a muscular partition between thorax and abdomen,it can bcum flat or dome shaped due to contraction and relaxation of muscles.
Q25. What is the other name of larynx?
Ans. it is also called adam’s apple.
Ans. amoeba lacks excretory organs. Waste products like ammonia and CO2 are passed outside through the process of diffusion. Contractile vacuole also plays an important role in
he process of excretion.
Q5. Describe the mechanism of urine formation in humans.
Ans. its completed in 4 steps: a) glomerular filtration: blood flows under pressure inside the glomerulus . as a result, it undergoes ultrafiltration. Urea, uric acid, amino acids, hormones, glucose, ions and water are filtered out and enter the Bowmans capsule. b) Reabsorption:the filtrate passes thru proximal convoluted tubule. The capillaries absorb all the useful components like: glucose, amino acids, ions etc. c) Tubular secretion: it occurs in distal convoluted tubule. It is the active secretion of waste by the blood capillaries into the urinary tubule. It ensures the removal of all the waste from the blood. d) Concentration of urine: 75% of water is reabsorbed in proximal convoluted tubule.some 10% of water reabsorbed in henles loop. e) Ureters : these are the narrow muscular tubesthat carry urine from kidneys to urinary bladder. f) Urinary bladder: it is a pear shaped sac that stores urine. g) Utrethra: it is a tube that takes urine from bladder to outside.
Q6. Why is trachea lined with the rings of cartilage?
Ans. Trachea is lined with the rings of cartilage to prevent it from collapsing.
Q7. Identify the respiratory organ in : a)leech b) cockroach c) crab d)mussel e)tadpole
Ans. a) skin b) trachea/ spiracles c) gills d) gills e) gills
Q8. How do plants exchange gases?
Ans. Plants exchange gases by the process of diffusion. Stomata help in the exchange of gases. CO2 gas is taken in and O2 is released by the process of photosynthesis.
Q9. What is the role of HCL in the stomach.
Ans. it has two roles: 1) kills the microbes that enter along with food. 2) Creates an acidic medium for pepsin functioning.
Q10. Name the raw materials of photosynthesis .
Ans. 4 requirements of photosynthesis are- 1 carbondioxide –is taken through stomata. 2 water and minerals- are transported to the leaves by the vessels. 3 chlorophyll-is present in the leaves of the plants. 4 sunlight-is absorbed by the chlorophyll present in the leaves.
Q11. Identify the specific mode of nutrition in : a) cuscuta b) ascaris c) mushroom d) deer e) humans Ans. a) parasitic b) parasitic c) saprophytic d)and e) holozoic
Q12. What is fermentation? What is its use?
Ans. fermentation is the kind of anaerobic respiration carried out by a unicellular organism called yeast. Yeast converts a sugar solution into alcohol and also releases CO2 Gas during this process. Its used in bakery and brewery industries.
Q13. Mention the raw materials needed for photosynthesis.
Ans. 4 requirements of photosynthesis are- 1 carbondioxide –is taken through stomatas 2 water and minerals- are transported to the leaves by the vessels. 3 chlorophyll-is present in the leaves of the plants. 4 sunlight-is absorbed by the chlorophyll present in the leaves.
Q14. Draw a well labeled diagram of human respiratory system.
. Q15. Draw a well labeled diagram of human excretory system.
. Q16. Draw a well labeled diagram of cross section of a leaf. Q17.
Draw a dig. Of stomata and write its 2 functions
Ans. functions:a) exchange of gases b) loss of extra water by transpiration
Q18. Draw a well labeled diagram of human digestive system
Q19. Name the 5 steps of holozoic nutrition
Ans. 1) ingestion:-- the process of intake of food. 3) digestion:-- changing complex food substances to simple form by the action of enzymes. 4) Absorption:-- digested food is absorbed in blood. 5) Assilmilation:-- the absorbed food components are converted into components of cytoplasm. 6) Egestion :-throwing out of waste.
Q20. Name the secretions and their role in digestion for the following glands::
Ans. Gland Secretion Function Salivary( mouth) Saliva( salivary amylase) Digests carbohydrate( starch) Gastric( stomach) Mucus, HCL, Pepsin Mucus has protective function HCL kills the microbes Pepsin digests proteins. Pancreas(abdomen) Pancreatic juice Trypsin digests proteins Amylase digests carbohydrate Lipase digests lipids and fats. Liver( abdomen) Bile Emulsification of fats
Q21 . why do aquatic organisms show a higher breathing rate?
Ans. this is bcos, water has low O2 content than the content of O2 in air.
Q22. why do we feel muscle cramps after heavy exercise?
Ans. this is bcos our cells and tissues become O2 deficient and start undergoing anaerobic respiration. This produces lactic acid and we feel muscle cramps.
Q23. Why is it advised to breathe thru nose?
Ans. The mucus and hair present in the nasal cavity help to filter the inhaled air.
Q24.What is a diaphragm?
Ans. it’s a muscular partition between thorax and abdomen,it can bcum flat or dome shaped due to contraction and relaxation of muscles.
Q25. What is the other name of larynx?
Ans. it is also called adam’s apple.
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