Chapter 4 Carbon and its Compounds Solutions
Question - 11 : - Would you be able to check if water is hard by using a detergent?
Answer - 11 : - It is not possible to check if water is hard by using a detergent because detergents are salts of ammonium or sulphonates of long chain carboxylic acids. Unlike soaps they do not react with calcium and magnesium to distinguish nature of water.
Question - 12 : - People use a variety of methods to wash clothes.
Answer - 12 : - 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
Agitation is necessary to get clean clothes as agitation aid soap micelles to trap the oil, grease or any other impurities that have to be removed. When they are being beaten or agitated, the particles are removed from the clothes’ surfaces and go into the water, thus cleaning the clothes.
Ethane, with the molecular formula C2H6 has
Answer - 13 : -
(a) 6 covalent bonds.
(b) 7 covalent bonds.
(c) 8 covalent bonds.
(d) 9 covalent bonds
Answer
Ethane, with the molecular formula C2H6 has 7 covalent bonds
Question - 14 : - Butanone is a four-carbon compound with the functional group
Answer - 14 : -
(a) carboxylic acid
(b) aldehyde
(c) ketone
(d) alcohol
Answer
Answer is option C i.e Ketone.
Question - 15 : - While cooking, if the bottom of the vessel is getting blackened on the outside, it means that
Answer - 15 : -
(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
Answer is option b. While cooking, if the bottom of the vessel is getting blackened on the outside indicates that the fuel is not burning completely.
Question - 16 : - Explain the nature of the covalent bond usingthe bond formation in CH3Cl
Answer - 16 : -
Carbon can neither lose 4 electrons nor do gain four electrons as these process make the system unstable due to requirement of extra energy. Therefore CH3Cl completes its octet configuration by sharing its 4 electrons with carbon atoms or with atoms of other elements. Hence the bonding that exists in CH3Cl is a covalent bonding.
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.
Question - 17 : - Draw the electron dot structures for
Answer - 17 : -
(a) ethanoic acid
(b) H2 S
(c) propanone
(d) F2
Answer
(a)
(b)
(c)
(d)
Answer - 18 : -
A homologous series is a series of compounds, which has the same functional group. This also contains similar general formula and chemical properties. Since there is a change in the physical properties, we can say that there would be an increase in the molecular size and mass.
For example, methane, ethane, propane, butane, etc. are all part of the alkane homologous series. The general formula of this series is CnH2n+2. Methane CH4 Ethane CH3CH3 PropaneCH3CH2CH3 Butane CH3CH2CH2CH3. It can be noticed that there is a difference of −CH2 unit between each successive compound.
Question - 19 : - How can ethanol and ethanoic acid be differentiated on the basis of their physical and chemical properties?
Answer - 19 : -
| Ethanol | Ethanoic acid |
| Does not react with sodium hydrogen carbonate | Bubbles and fizzes with hydrogen carbonate |
| A good smell | Smells like vinegar |
| No action in litmus paper | Blue litmus paper to red |
| Burning taste | Sour taste |
Question - 20 : - 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 - 20 : -
Micelle formation takes place because of the dirt particles in water and clean water. There are two mediums that are involved: one is pure water and the other being dirt (also called as impurities). The soap also has two mediums:
(i) organic tail and
(ii) ionic head
So the organic tail mixes and dissolves with the dirt whereas the oil or grease and ionic head dissolves and mixes with the water. Therefore, when the material to be cleaned is removed from the water, the dirt is taken off by the soap molecules in the water. Hence, the soap cleans by forming closed structures by the mutual repulsion of the micelles (positively charged heads).