CBSE Class 10 Science Carbon And Its Compounds Worksheet Set 03

Question. Bromine reacts with saturated hydrocarbon at room temperature in the
(a) absence of sunlight
(b) presence of water
(c) presence of sunlight
(d) presence of hydrochloric acid
Answer : C

Question. The upper and lower homologue of C₂H₅OH are respectively
(a) methyl alcohol and butyl alcohol
(b) ethyl alcohol and propyl alcohol
(c) butyl alcohol and propyl alcohol
(d) propyl alcohol and methyl alcohol
Answer : D

Very Short Answer Questions

Question. What is a hydrocarbon?
Answer : It is a compound of hydrogen and carbon.

Question. Name two types of hydrocarbon.
Answer : Hydrocarbon – Saturated and unsaturated.

Question. What is catenation?
Answer : Carbon has the unique ability to form bonds with the other atoms of carbon which gives rise to large molecules. This property of self linking is called catenation.

Question. Why covalent compounds have low melting and boiling points?
Answer : As the bond is formed by sharing of electrons between two atoms. Intermolecular forces are small between the covalent compounds. These bonds break easily.

Question. Define catalyst.
Answer : Catalyst are substances that cause a reaction with a change in rate of reaction, without itself undergoing any change.
Example: Micelle acts as a catalyst to convert unsaturated hydrocarbon into saturated hydrocarbon.

Question. Give the full form of IUPAC.
Answer : IUPAC → International Union of Pure and Applied Chemistry.

Question. How can we convert CH₃CH₂OH into C₂H₄ ?
Answer : By adding conc. sulphuric acid into it which acts as dehydrating agent and removes water from it.

Question. What is the melting point of acetic acid?
Answer : M.P. = 290 K.

Question. How can you convert ethene into ethane?
Answer : By adding hydrogen to ethene in the presence of a catalyst.

Question. What is esterification reaction?
Answer : The reaction in which alcohol reacts with carboxylic acid to produce a new compound called ester is called esterification.

Question. What is isomerism?
Answer : A property in which a compound can exist in different structural formula but its molecular formula remains the same.

Question. What is hydrophilic?
Answer : The substance showing attraction towards water is called hydrophilic.

Question. ‘‘Saturated hydrocarbons burn with a blue flame while unsaturated hydrocarbons burn with a sooty flame’’. Why?
Answer. An unsaturated hydrocarbon has high concentration of carbon, which does not get oxidised by the atmospheric oxygen. Thus, unburnt carbon appears in the form of soot and hence the flame is sooty.

Question. Write the next higher homologue of the following : (i) C₃H₆ (ii) C5H₈
Answer. (i) C₄H₈ (ii) C₆H₁₀

Question. Write the name and structure of an aldehyde with 4 carbon atoms.
Answer. C₃H₇ CHO (Butanal)

Question. Draw the electron dot structure of ethane (C₂H₆).
Answer. 

Question. Draw the structure of pentanal (C₄H₉CHO).
Answer.

Question. Name the functional group present in each of the following compounds.

Answer. C₃H₇OH — Alcoholic group

Question. Draw the structure of ethene molecule (C₂H₄).
Answer.

Question. (a) Name the functional group present in propanal (C₃H₆O).
Answer. Aldehyde group

(b) Name the fourth (4th) member of alkene series.
Answer. Pentene

Question. (a) Name the type of reaction represented by the following equation :

Answer. Esterification

(b) Draw the structure of ethanol molecule.
Answer.

Question. Why is the conversion of ethanol to ethanoic acid considered an oxidation reaction?
Answer. Conversion of ethanol to ethanoic acid is considered an oxidation reaction since it involves:
(i) addition of oxygen to the ethanol molecule
(ii) removal of hydrogen from the ethanol molecule.

Question. (a) Draw the structure of the simplest ketone.
Answer.

Question.(b) Draw the structure of CH₃COOH molecule.
Answer.

Question. (a) Name the compound formed when ethanol is warmed with ethanoic acid in the presence of few drops of concentrated. H2SO4.
Answer. Ethyl ethanoate (an ester)

Question.(b) Write a chemical equation to represent the reaction of ethanol with acidified solution of potassium dichromate.
Answer.

Question. (a) What happens when a small piece of sodium is dropped into ethanol?
Answer. Sodium reacts with ethanol to form sodium ethoxide and liberates hydrogen gas.

Answer. Acetone or propanone

Question. Why does carbon form compounds mainly by covalent bonding?
Answer. Carbon has four valence electrons. Thus, it is not in a position to donate/accept four electrons so as to acquire a stable neon gas like structure. Thus, in order to enter into a chemical reaction,it shares its valence electrons with other elements.

Question. (a) What would be observed on adding a 50% solution of alkaline potassium permanganate drop by drop to some warm ethanol taken in a test tube?
(b) Write the name of the compound formed during the chemical reaction.
Answer. (a) The pink colour of potassium permanganate would be discharged.
(b) Ethanoic acid.

Question. (a) How would you distinguish experimentally between an alcohol and a carboxylic acid on the basis of a chemical property?
Answer. Ethanol does not react with sodium carbonate. However, carboxylic acid reacts with sodium carbonate with the liberation of carbon dioxide gas which turns limewater milky.

(b) Name the gas evolved when ethanoic acid is added to sodium carbonate. How would you prove the presence of this gas?
Answer. Carbon dioxide gas.
The gas when passed through limewater turns the limewater milky.

Question. What is a functional group in a carbon compound. Identify the functional group present in CH₃COOH and C₂H₅OH.
Answer. An atom or a group of atoms which gives the same characteristic properties to a compound is called a functional group.
Functional group in : CH₃COOH — Carboxylic acid group
C₂H₅OH — Alcoholic group

Question. (a) name the compound CH₃CH₂OH and identify its functional group.
Answer. Ethyl alcohol
Alcoholic group.

(b) What is the difference in the molecular formula of any two consecutive members of a homologous series of organic compounds?
Answer. CH₂

Question. Why are covalent compounds generally poor conductors of electricity?
Answer. Covalent compounds are formed by the sharing of valence electrons. As such they do not have cations or anions which could migrate to the opposite poles of an electrolytic cell. Thus, they do not conduct electric current.

Question. Write the names of the functional groups in :

Answer. (i) Ketonic group (ii) Aldehydic group

Short Answer Questions

Question. What is an homologous series? Explain with an example.
Answer : A homologous series is a series of carbon compounds that have different numbers of carbon atoms but contain the same functional group.

 

II. Distriction based on chemical properties

(i) Action with sodium hydrogen carbonate: On adding a small amount of sodium hydrogen carbonate to ethanoic acid, carbon dioxide gas is evolved with brisk effervescence. However, no such reaction noticed in case of ethanol.

(ii) Action with caustic alkalies Ethanoic acids reacts with both sodium hydroxide (NaOH) and potassium hydroxide (KOH) to form corresponding salt and water. Ethanol fails to react with either of these.

 

Question. Why does micelle formation take place when soap is added to water? Will a micelle be formed in other solvents such as ethanol also?

Answer : A soap is a sodium or potassium salt of long chain fatty acids. It has one polar end and one non-polar end. The polar end is hydrophilic in nature i.e., this end is attracted towards water. The non-polar end is hydrophobic but lyophilic, i.e., it is attracted towards hydrocarbons. When soap is added to water, soap molecules arrange themselves in a cluster to keep the non- polar portion out of water such that the non-polar ends are in the interior of the cluster and the polar ends are on the surface of the cluster. Since the dirt present on clothes is organic in nature and insoluble in water, the hydrophobic ends of the clusters attach themselves to the dirt. This cluster formation in which the dirt is entrapped is the micelle. Micelle formation does not occur in alcohol because the alkyl chain of soap becomes soluble in alcohol.

Answer : Carbon burns in oxygen (air) to form carbon dioxide and water.

During this reaction a large amount of heat and light are released. Further, once ignited carbon and its compounds keep on burning without the requirement of additional energy. Hence, they are used as fuels.

 

Question. Explain the formation of scum when hard water is treated with soap.

Answer : Soap does not work properly when the water is hard. A soap is a sodium or potassium salt of long chain fatty acids. Hard water contains salts of calcium and magnesium. When soap is added to hard water, calcium and magnesium ions present in water displace sodium or potassium ions from the soap molecules forming an insoluble substance called scum. A lot of soap is wasted in the process.

Question : The by-product in soap industry is: