Class 10 - Chemistry - Carbon and Its Compounds
Ethane, with the molecular formula C2H6 has
(a) 6 covalent bonds.
(b) 7 covalent bonds.
(c) 8 covalent bonds.
(d) 9 covalent bonds.
Correct Option: - (b) 7 covalent bonds.
One covalent bond is between 2 carbons and rest is with 6 hydrogens.
Butanone is a four-carbon compound with the functional group
(a) carboxylic acid.
Correct Option: - (c) Ketone.
The functional group of butanone is ketone.
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.
Correct Option: - (b) the fuel is not burning completely.
Explain the nature of the covalent bond using the bond formation in CH3Cl.
Carbon forms bond by sharing its four electrons with other atoms.
Such bonds which are formed by the sharing of an electron pair between two atoms are known as covalent bonds.
In covalent bonding, both the atoms share the valence electrons, i.e., the shared electrons belong to the valence shells of both the atoms.
Here, carbon requires 4 electrons to complete its octet, while each hydrogen atom requires one electron to complete its duplet.
Also, chlorine requires an electron to complete the octet.
Therefore, all of these share the electrons and as a result, carbon forms 3 bonds with hydrogen and one with chlorine.
Draw the electron dot structures for
(a) ethanoic acid.
(d) F2 .
Electron dot structures of
What is a homologous series? Explain with an example.
A homologous series is a series of carbon compounds that have different numbers of carbon atoms but contain the same functional group.
For example, methane, ethane, propane, butane, etc. are all part of the alkane homologous series. The general formula of this series is CnH2n+2.
It can be noticed that there is a difference of −CH2 unit between each successive compound.
How can ethanol and ethanoic acid be differentiated on the basis of their physical and chemical properties?
Difference between ethanol and ethanoic acid on the basis of their physical and chemical properties are as follows:-
Metal Carbonates /Metal Hydro carbonates + carboxylic acid à salt + water + carbon dioxide
For Example: - 2CH3COOH + Na2CO3 → 2CH3COONa + H2O + CO2
Metal Carbonates/ Metal Hydrogen carbonates + Alcohols à No reaction
For Example: - CH3CH2OH + Na2CO3 à No reaction
Why does micelle formation take place when soap is added to water? Will a micelle be formed in other solvents such as ethanol also?
A soap molecule has 2 ends one is hydrophilic i.e. it dissolves in water, and the other one is hydrophobic i.e. it dissolves in the oil or dirt.
Micelle formation takes place when soap is added to water as the hydrophobic part attracts dirt and grease.
No micelle will be formed in other solvents such as ethanol because the alkyl chain of soap becomes soluble in alcohol.
Micelles can be formed only around suspended molecules of oil in a mixture.
Ethanol is a very good solvent and it can even dissolve oil to form a clear solution.
Why are carbon and its compounds used as fuels for most applications?
Most of the carbon compounds give a lot of heat and light when burnt in air.
Saturated hydrocarbons burn with a clean flame and no smoke is produced.
The carbon compounds, used as a fuel, have high calorific values.
Therefore, carbon and its compounds are used as fuels for most applications.
Explain the formation of scum when hard water is treated with soap.
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.
What change will you observe if you test soap with litmus paper (red and blue)?
Since soap is basic in nature, it will turn red litmus blue. However, the colour of blue litmus will remain blue.
What is hydrogenation? What is its industrial application?
When hydrogen is added to unsaturated hydrocarbons in the presence of catalysts such as palladium or nickel they give rise to saturated hydrocarbons.
Catalysts are substances that cause a reaction to occur or proceed at a different rate without the reaction itself being affected.
Commonly used catalyst in the hydrogenation of vegetable oils is nickel.
Vegetable oils generally have long unsaturated carbon chains while animal fats have saturated carbon chains.
Oils containing unsaturated fatty acids should be chosen for cooking.
Which of the following hydrocarbons undergo addition reactions?
C2H6, C3H8, C3H6, C2H2 and CH4
Unsaturated hydrocarbons undergo addition reactions. Being unsaturated hydrocarbons,
C3H6 and C2H2 undergo addition reactions.
Give a test that can be used to differentiate chemically between butter and cooking oil.
Butter contains saturated fats. Therefore, it cannot be hydrogenated. On the other hand, oil has unsaturated fats.
That is why it can be hydrogenated to saturated fats (solids).
Bromine water test can be used to differentiate chemically between butter and cooking oil.
Add bromine water to a little of cooking oil and butter taken in separate test tubes.
Explain the mechanism of the cleaning action of soaps.
The mechanism of the cleaning of soap can be described as below:-