AP 10th Class Physical Science 4th Lesson Questions and Answers Carbon and Its Compounds

AP State Board new syllabus AP Board Solutions Class 10 Physics 4th Lesson Carbon and Its Compounds Questions and Answers.

10th Class Physical Science 4th Lesson Carbon and Its Compounds Questions and Answers

10th Class Physics 4th Lesson Questions and Answers (Exercise)

Question 1.
Ethane, with the molecular formula C2H6 has
a) 6 covalent bonds.
b) 7 covalent bonds.
c) 8 covalent bonds.
d) 9 covalent bonds.
Answer:
b) 7 covalent bonds.

Question 2.
Butanone is a four-carbon compound with the functional group.
a) carboxylic acid.
b) aldehyde.
c) ketone.
d) alcohol.
Answer:
c) ketone.

Question 3.
While cooking, if the bottom of the vessel is getting blackened on the outside, it means that
a) the food is not cooked completely,
b) the fuel is not burning completely.
c) the fuel is wet.
d) the fuel is burning completely.
Answer:
b) the fuel is not burning completely.

Question 4.
Explain the nature of the covalent bond using the bond formation in CH₃Cl.
Answer:

1. The covalent bond in CH₃Cl is formed by sharing electrons between carbon and hydrogen or chlorine atoms.
2. In the formation of CH₃Cl, one carbon atom shares one of its valence electrons with each of the three hydrogen atoms and one with the chlorine atom.
3. Simultaneously; the hydrogen atom shares its single valence electron with the carbon atom.
4. As a result, a total of 4 pairs of electrons (4 bonds) are shared between the carbon atom and the hydrogen and chlorine atoms, satisfying the octet/duet.
5. This sharing of electrons creates a covalent bond, specifically single covalent bonds, between carbon and hydrogen and carbon and chlorine.
6. The nature of the covalent bond in CH₃Cl is characterized by the sharing of electrons between atoms to achieve a stable electron configuration, allowing all atoms to fill their outermost electron shells and become more stable and less reactive.
7. This sharing of electrons creates a strong connection between the atoms in the molecule, holding them together.
8. So, a covalent bond is a strong and stable bond.

Question 5.
Draw the electron dot structures for
a) ethanoic acid
b) H₂S
c) propanone
d) F₂.
Answer:
Electron dot structures :

Question 6.
What is a homologous series ? Explain with an example.
Answer:
Homologous series : A series in which every succeeding compound differs from the previous one by – CH₂ group.

Example : The general formula for homologous series of alkanes is C_nH_{2n + 2}. CH₄ (Methane), C₂H₆ (Ethane), C₃H₈ (Propane) and C₄H₁₀O (Butane)

Every homologous series have general formula. In alkane single bond is functional group, in alkane double bond and alkyne triple bond.

Question 7.
How can ethanol and ethanoic acid be differentiated on the basis of their physical and chemical properties ?
Answer:

Ethanol	Ethanoic Acid
1) Ethanol has a pleasant smell	1) Ethanoic acid has the smell of Vinegar.
2) The boiling point of ethanol is 351 K.	2) The boiling point of ethanoic acid is 391 K.
3) Ethanol reacts with alkaline KMnO4 to give ethanoic acid.	3) Ethanoic acid does not react with alkaline KMnO4.
4) Ethanol does not react with sodium hydrogen carbonate.	4) It gives brisk effervescence with sodium hydrogen carbonate CH3COOH + NaHCO4 → CH3COONa + H2O + CO2↑

Question 8.
Why does micelle formation take place when soap is added to water? Will a micelle be formed in hither solvents such as ethanol also ?
Answer:
When soap is added to water, micelle formation takes place. This is because the hydrocarbon chains of soap molecule are hydrophobic which are insoluble in water, but the ionic ends of soap molecules are hydrophilic and hence soluble in water. Since soap is soluble in ethanol, so micelle for motion does not occur.

Question 9.
Why are carbon and its compounds used as fuels for most applications ?
Answer:
Carbon and its compounds are used as fuels because they burn in air releasing a large amount of heat energy
C + O₂ → CO₂ + Heat
CH₄ + O₂ → CO₂ + H₂O + Heat and tight.

Question 10.
Explain the formation of scum when hard water is treated with soap.
Answer:
Scum is formed when soap molecule reacts with calcium and magnesium ions present in hard water. The formation of scum slows down the cleaning action and also results in wastage of soap.

Question 11.
What change will you observe if you test soap with litmus paper (red and blue) ?
Answer:
Soaps are alkaline, so it will turn red litmus blue and no effect on blue litmus paper.

Question 12.
What is hydrogenation? What is its industrial application ?
Answer:
Hydrogenation : Hydrogenation is a process in which a substance reacts with hydrogen in the presence of nickel or palladium as catalyst.

Industrial application : The process of hydrogenation is used to prepare vegetable ghee from vegetable oil.

Question 13.
Which of the following hydrocarbons undergo addition reactions: C₂H₆, C₃H₈, C₃H₆, C₂H₂ and CH₄ ?
Answer:
C₃H₆ and C₂H₂ are unsaturated hydrocarbons, therefore, they will undergo addition reactions.

Question 14.
Give a test that can be used to differentiate between saturated and unsaturated hydrocarbons.
Answer:
Add bromine water to each of them. Cooking oil will decolourise bromine water showing that it is unsaturated, whereas butter will not decolourise bromine water showing that is saturated.

Question 15.
Explain the mechanism of the cleaning action of soaps.
Answer:
Cleaning action of Soaps:

1. The dirt present on clothes is organic in nature and insoluble in water.
2. Therefore, it cannot be removed by only washing with water.
3. When soap is dissolved in water, its hydrophobic ends attach themselves to the dirt and remove it from the cloth.
4. Then, the molecules of soap arrange themselves in micelle formation and trap the dirt at the centre of the cluster.
5. These micelles remain suspended in the water. Hence the dust particles are easily rinsed away by water.

10th Class PS 4th Lesson Questions and Answers (InText)

Page No. 130

Question 1.
What would be the electron dot the formula CO₂?
Answer:

Question 2.
What would be the electron dot structure of a molecule of sulphur which is made up of eight atoms of sulphur?
Answer:

Page No. 142

Question 3.
How many structural isomers can you draw for pentane ?
Answer:
We can draw three structural isomers of pentane (C₅H₁₂)

Question 4.
What are the two properties of carbon, which lead to the huge number of carbon compounds we see around us ?
Answer:
Catenation and tetravalency.

Question 5.
What will be the formula and electron dot structure of cyclopentane ?
Answer:

Question 6.
Draw the structures for the following compounds,
i) Ethanoic acid
ii) Bromopentane
iii) Butanone
iv) Hexanal.
Are structural isomers possible for bromopentane ?
Answer:

Yes, structural isomers are possible for bromopentane.

Question 7.
How would you name the following compounds ?
i) CH₃ – CH₂ – Br

Answer:
i) Bromoethane
ii) Methanal
iii) 1 – Hexyne

Page No. 148

Question 8.
Why is the conversion of ethanol to ethanoic acid an oxidation reaction ?
Answer:

Since the conversion of ethanol to ethanoic acid involves the addition of oxygen to ethanol, it is an oxidation reaction.

Question 9.
A mixture of oxygen and ethyne is burnt for welding. Can you tell why a mixture of ethyne and air is not used?
Answer:
Ethyne with oxygen gives enough heat can be used for welding whereas if it is burnt in air which contains nitrogen and other inactive gaseous contents, sufficient oxygen is not available for burning ethyne to give the required heat.

Page No. 154

Question 10.
How would you distinguish experimentally between an alcohol and a carboxylic acid ?
Answer:

Test	Alcohol	Carboxylic acid
1) Litmus test	No change in colour	Blue litmus solution turns red
2) Sodium carbonate	No action	Brisk effervescence is produced
3) Sodium metal test	H2 is given out with effervescence	H2 is produced but no effervescence

Question 11.
What are oxidising agents ?
Answer:
Those substances which give oxygen or replace hydrogen on reaction with other compounds are known as oxidising agents. For example, potassium permanganate (KMnO₄.

Page No. 158

Question 12.
Would you be able to check if water is hard by using a detergent ?
Answer:
No, because detergent is equally effective in hard water as well as soft water.

Question 13.
People use a variety of methods to wash clothes. Usually after adding the soap, they ‘beat’ the clothes on a stone, or beat it with a paddle, scrub with a brush or the mixture is agitated in a washing machine. Why is agitation necessary to get clean clothes?
Answer:
Soap is able to remove dirt from clothes only in thin layers. Therefore, agitation or some similar activity is necessary so that totcil dirt is removed in layers of miscelles on continuous agitation and washing.

Group Activity Page No : 162

(I) Use molecular model kits to make models of the compounds you have learnt in this Chapter.

(II) • Take about 20 mL of castor oil/cotton seed oil/linseed oil/soyabean oil in a beaker.
Add 30 mL of 20 % sodium hydroxide solution. Heat the mixture with continuous stirring for a few minutes till the mixture thickens. Add 5 – 10 g of common salt to this. Stir the mixture well and allow it to cool.
• You can cut out the soap in-fancy shapes. You can also add perfume to the soap before it sets.
Answer:
Do yourself.

AP 10th Class Physical Science Chapter 4 Questions and Answers (Lab Activities)

Activity – 4.1 (Page. No. 122)

Question 1.
1. Make a list of ten things you have used or consumed since the morning.
2. Compile this list with the lists made by your classmates and then sort the items into
the following Table.
3. If there are items which are made up of more than one material, put them into both the relevant columns of the table.

Things made of metal	Things made of glass/clay	Others

Answer:

S.No.	Things made of metal	Things made of glass/clay	Others
1)	Fan	Cup	Clothes
2)	Refrigerator	Tumbler	Tooth brush
3)	Spoon	TV	Tooth Paste
4)	TV	Bulb	Shoes
5)	Pen	Mobile phone	Purse
6)	Telephone	Watch	Pencil
7)	Key	Frame	Bread
8)	Coins	Rower vase	Milk
9)	Tiffin Box	Statue	Books
10)	Bus	Bottle	Chair

Activity – 4.2 (Page. No. 140)

Question 2.
Calculate the difference in the formulae and molecular masses for
(a) CH₃OH and C₂H₅OH
(b) C₂H₅OH and C₃H₇OH
(c) C₃H₇OH and C₄H₉OH.
Answer:
Formulae difference and molecular mass difference in all pairs are – CH₂ and 14 amu respectively.

* Is there any similarity in these three ?
Answer:
All these have same functional group (alcohol) and thus have similar chemical properties.

* Arrange these alcohols in the order of increasing carbon atoms to get a family. Can we call this family a homologous series ?
Answer:
CH₃OH, C₂H₅OH, C₃H₇OH, C₄H₉OH. This is a homologous series of alcohols.

* Generate the homologous series for compounds containing up to four carbons for
the other functional groups given in Table 4.3. (T.B. Page 138).
Answer:
Homologous series of Halides : CH₃Cl, C₂H₅Cl, C₃H₇Cl, C₄H₉Cl
Homologous series of Aldehydes : CH₂CHO, C₂H₅CHO, C₃H₇CHO
Homologous series of Ketones : C₂H₆CO, C₃H₈CO
Homologous series of Carboxylic Acids : CH₃COOH, C₂H₅COOH, C₃H₇COOH

Activity – 4.3 (Page. No. 144)

Question 3.
i) Take some carbon compounds (naphthalene, camphor, alcohol) one by one on a spatula and burn them.
ii) Observe the nature of the flame and note whether smoke is produced.
iii) Place a metal plate above the flame. Is there a deposition on the plate in case of
any of the compounds ?
Answer:

Carbon Compounds	Name of Flame	Deposits on Metal plate
1) Camphor	Smoky flame	Carbon deposits
2) Alcohol	Non-sooty flame	No carbon
3) Acetone	Non-sooty flame	No carbon
4) Napthalene	Smoky flame	Carbon deposits

Activity – 4.4 (Page. No. 144)

Question 4.
Light a bunsen burner, when do you get a
i) Yellow, sooty flame
ii) blue flame ?
Answer:
i) You get a yellow, sooty flame if some of the holes in the bottom of burner are blocked and the burning does not get sufficient oxygen.
ii) You get a blue flame if all the holes are open and sufficient oxygen rich air is available.

Activity – 4.5 (Page. No. 146)

Question 5.
Take about 3 mL of ethanol in a test tube and warm it gently in a water bath. Add a 5% solution of potassium permanganate drop by drop to this solution.
Answer the following questions :
a) Does the colour of potassium permanganate persist when it is added initially ?
b) Why does the colour of potassium permanganate not disappear when excess is added ?
Answer:
a) Initially colour of potassium permanganate disappears because coloured permanganate ions of potassium permanganate are consumed to oxidise ethanol to ethanoic acid.

b) When excess potassium permanganate is added, colour does not disappear because there is no alcohol left and hence there is no reaction.

Activity – 4.6 (Page. No. 148)

Question 6.
Teacher’s demonstration –
Drop a small piece of sodium, about the size of a couple of grains of rice, into ethanol (absolute alcohol)-
a) What do you observe ?
b) How will you test the gas evolved ?
Answer:
a) Vigorous reaction occurs and a gas (H₂) is bubbled out.
b) The gas evolved burns with a pop sound when exposed to burning matchstick.

Activity – 4.7 (Page. No. 150)

Question 7.
Compare the pH of dilute acetic acid and dilute hydrochloric acid using both litmus paper and universal indicator.
a) Are both acids indicated by the litmus test ?
b) Does the universal indicator show them as equally strong acids ?
Answer:
a) Both acids, acetic acid and dilute hydrochloric acid turn litmus paper red.

b) Universal indicator shows different colours with acetic acid and hydrochloric acid showing clearly that hydrochloric acid is a stronger acid than acetic acid.

Activity – 4.8 (Page. No. 152)

Question 8.
What is the esterification reaction ?
Write the procedure to conduct an esterification reaction.
(OR)
Write the Reaction of ethanoic acid with alcohol.
Answer:
1. Esterification reaction :

1. Esters are most commonly formed by reaction of an acid and an alcohol.
2. Ethanoic acid reacts with absolute ethanol in the presence of an acid catalyst to give an ester.
3. 
4. Generally, esters are sweet-smelling substances.

2. Procedure of Esterification reaction :

1. Take 1 mL ethanol (absolute alcohol) and lmL glacial acetic acid along with a few drops of concentrated sulphuric acid in a test tube.
2. Warm in a water bath for at least five minutes as shown in Figure.
3. Pour into a beaker containing 20 – 50 mL of water and smell the resulting mixture.

Activity – 4.9 (Page. No. 152)

Question 9.
How does ethanoic acid react with carbonates and hydrogen carbonates? Write an activity.
(OR)
Explain the reaction of ethanoic acid with carbonates and hydrogen carbonates through an activity.
Answer:
Reaction with carbonates and hydrogen carbonates Ethanoic acid reacts with carbonates and hydrogen carbonates to give rise to a salt, carbon dioxide and water. The salt produced is commonly called sodium acetate.

Activity :

1. Take a spatula full of sodium carbonate in a test tube and add 2 mL of dilute ethanoic acid.
2. You can observe that a gas will be released.
3. Pass the gas produced through freshly prepared lime-water.
4. The lime water will be changed into milky white.
5. So, we can say that the gas produced by the reaction between ethanoic acid and sodium carbonate is carbon dioxide.
6. Repeat this Activity with sodium hydrogen carbonate instead of sodium carbonate.
7. The equations of the reactions :
   2CH₃COOH + Na₂CO₃ → 2CH₃COONa + H₂O + CO₂
   CH₃COOH + NaHCO₃ → CH₃COONa + H₂O + CO₂

Activity – 4.10 (Page. No. 154)

Question 10.
Write an activity that demonstrates the effect of soap in cleaning. Explain the reason.
Answer:

1. Take about 10 mL of water each in two test tubes.
2. Add a drop of oil (cooking oil) to both the test tubes and label them as A and B.
3. To test tube B, add a few drops of soap solution.
4. Now shake both test tubes vigorously for the same period of time.
5. You can see the oil and water layers separately in test tube B immediately after you stop shaking them.
6. Leave the test tubes undisturbed for some time and observe.
7. The oil layer separates out first in Test tube B.
8. This activity demonstrates the effect of soap in cleaning.

Reason :

1. Most dirt is oily in nature and as you know, oil does not dissolve in water.
2. The molecules of soap are sodium or potassium salts of long-chain carboxylic acids.
3. The ionic end of soap interacts with water while the carbon chain interacts with oil.
4. The soap molecules, thus form structures called micelles where one end of the molecules is towards the oil droplet while the ionic-end faces outside.
5. This forms an emulsion in water.
6. The soap micelle thus helps in pulling out the dirt in water and we can wash our clothes clean.

Activity – 4.11 (Page. No. 158)

Question11.
Write an activity to compare the effect of soap in hard water and distilled water.
Answer:

1. Take about 10 mL of distilled water (or rainwater) and 10 mL of hard water (from a tubewell or hand pump) in separate test tubes.
2. Add a couple of drops of soap solution to both.
3. Shake the test tubes vigorously for an equal period of time and observe the amount of foam formed.
4. More foam forms in the test tube with distilled water.
5. A white curdy precipitate forms in the test tube with hard water.
6. This is caused by the reaction of soap with the calcium and magnesium salts, which cause the hardness of water.

Activity – 4.12 (Page. No. 158)

Question 12.
Write an activity to compare the effect of soap and detergents with hard water.
(OR)
How do you prove that detergents are better than soaps? Explain the reason.
Answer:

1. Take two test tubes with about 10 mL of hard water in each.
2. Add five drops of soap solution to one and five drops of detergent solution to the other.
3. Shake both test tubes for the same period.
4. More foam forms in the test tube with detergent.
5. A white curdy precipitate forms in the test tube with soap.

Reason :

1. Detergents are generally sodium salts of sulphonic acids or ammonium salts with chlorides or bromides ions, etc. Both have long hydrocarbon chain.
2. The charged ends of these compounds do not form insoluble precipitates with the calcium and magnesium ions in hard water.
3. Thus, they remain effective in hard water.