Please refer to VBQs for Class 10 Science Carbon And Its Compound. All value based questions for English Class 10 have been provided with solutions. We have provided below important values questions and answers. Students should learn these solved VBQs for Class 10 Science as these will help them to gain more marks and help improve understanding of important topics.
Carbon And Its Compound VBQs Class 10 Science with Answers
Multiple Choice Questions
Question. Pentane with molecular formula C5H12 has
(a) 12 covalent bonds
(b) 16 covalent bonds
(c) 18 covalent bonds
(d) 15 covalent bonds
Question. Three of the four compounds belong to a homologous series. Identify the odd one out.
Question. Which of these is not a property of Carbon?
(c) Formation of ionic bonds
(d) Tendency to form multiple bonds
Question. which of the following statements is correct about the given electron dot structure
a. The compound has 8 bonds of which one is a double bond
b. The compound is formed of all single bonds of which one is a C-C bond.
c. The electrons in every shell of the atoms are shown in the structure.
d. Electron dot structure doesn’t help to identify the bonds in a compound
Question. Number of covalent bonds in cyclobutane is
Question. Which of the following is not an alkane, alkene or alkyne?
Question. Which of the following homologue does not belong to a given homologous series
Assertion Reason Type Questions
Following questions consist of two statements – Assertion (A) and Reason (R). Answer these questions selecting the appropriate option given below:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true
Question. Assertion(A): Diamond and graphite are allotropes of carbon.
Reason (R): Some elements can have several different structural forms while in the same physical state. These forms are called allotropes.
Question. Assertion (A): Diamond is not good conductor of electricity.
Reason: It has no free electrons.
Question. Assertion (A): Graphite is slippery to touch.
Reason: The various layers of carbon atoms in graphite are held together by weak forces of attractions.
Question. Assertion(A): The functional group present in alcohols is – OH.
Reason (R): It is the same group as present in water, hence water and alcohol have similar properties.
Case Study Based
1. Read the following carefully.
In covalent compounds atoms share valence electrons to satisfy the octet. Each atom shares one pair or two pairs or three pairs of electrons depending on their combining capacity. In electron dot structures only number of valence electrons are shown around the symbols of constituent atoms. Carbon using its valency of four can make either single, double or triple bonds with other carbon atoms or any other atoms. Carbons self-linking property is called catenation. In hydrocarbons carbon makes aliphatic or cyclic molecules they are either saturated or unsaturated. Based on these facts Read the following paragraph and answer the questions given below.
An element X combines with Y to form a colourless odourless gas, Z which turns lime water milky is the major constituent of all organic molecules. Five X atoms combines with hydrogens to form a cyclic saturated hydrocarbon J and aliphatic unsaturated hydrocarbon Q.Q is used in gas welding.
a) Identify compound Z and draw its electron dot structure.
b) Write the chemical formula and IUPAC name of compound Q
c) What is the common name of Q
d) How many single covalent bonds are present in compound J?
e) Draw the structure of J and write its chemical formula.
a) Z is CO2 its electron dot structure is
2. Read the following and answer any four questions from 1(i) to 1(v).
A series of organic compounds having the same functional group, with similar or almost identical chemical characteristics in which all the members can be represented by the same general formula and the two consecutive members of the series differ by -CH2 group or 14 mass unit in their molecular formulae is called a homologous series. For example, all the members of the alcohol family can be represented by the general formula, CnH2n+1OH where n may have the values 1, 2, 3, etc. The various members of a particular homologous series are called homologues. The physical properties such as density, melting point, boiling point, solubility etc. of the members of a homologous series show almost regular variation in ascending and descending the series.
Question. Which one of the following is not a characteristic of members of a homologous series?
(a) They possess varying chemical properties.
(b) Their physical properties vary in a regular and predictable manner.
(c) Their formulae fit the general molecular formula
(d) Adjacent members differ by one carbon and two hydrogen atoms
Question. All the members of homologous series of alkynes have the general formula
Question. Which of the following statements is not correct?
(a) A common functional group is present in different members of a homologous series.
(b) Two consecutive members of a homologous series differ by a -CH3 group.
(c) The molecular mass of a compound in the series differs by 14 a.m.u. from that of its neighbour.
(d)All the members of a homologous series have common general methods of preparation.
Question. Identify the correct statements:
(a) As the molecular mass increases in any homologous series, a gradation in physical properties is seen.
(b) The melting and boiling points decrease with increasing molecular mass.
(c) As the molecular mass increases in any homologous series, variation in chemical properties is observed a gradation in physical properties is seen.
(d) Adjacent members in a homologous series differ by 18u.
Short Answer Type Questions
Question. An element of group 14 has two common allotropes, A and B. A is very hard and is bad conductor of electricity while B is soft to touch and good conductor of electricity. Identify the element and its allotropes.
Answer. Element is carbon
A is Diamond.
B is graphite
Question. Why homologous series of carbon compounds are so called? Write chemical formula of two consecutive members of a homologous series and state the part of these compounds that determines their
(i) physical properties, and
(ii) chemical properties.
Answer. The series consists of members of same family with similar physical and chemical properties, therefore, called homologous series (i) CH3OH, and (ii) CH3CH2OH are two consecutive members of homologous series. Alkyl group —CH3 and —CH3CH2 part determines physical properties. Functional group —OH determines chemical properties of the compounds.
Question. List any two properties of homologous series.
Answer. i) They show gradation in physical properties.
ii) Similarity in chemical properties
iii) They can be represented by a general formula
(any two properties can be written)
Question. Give the general formula of alkanes. Write the name, structural formula and physical state of the compound containing:
(i) 3-carbon atoms
(ii) 8-carbon atoms.
Answer. General formula of alkanes is CnH2n+2 where n = 1, 2, 3…
(i) Propane, CH3—CH2—CH3 Propane is a gas.
(ii) CH3—CH2—CH2—CH2—CH2—CH2—CH2—CH3 Octane is a liquid
Question. Compare the structures of diamond and graphite.
Answer. In diamond, each carbon atom is bonded to four other carbon atoms forming a rigid three dimensional structure.
In graphite, each carbon atom is bonded to three other carbon atoms in the same plane giving a hexagonal array. One of these bonds is a double bond.
Question. Compare the catenation ability of Carbon and Silicon.
Answer. Carbon and Silicon, both with valency 4, have the ability to form covalent bonds by sharing of electrons. Both show the ability of self- combination- catenation.
In Carbon, the small size of carbon atoms, as also the formation of strong bonds by Carbon atoms among themselves and with atoms of other elements, makes carbon compounds very stable.
Silicon can form compounds having Si chains of up to 7 or 8 atoms. But due to weak bonds, these compounds are not stable
Question. Alkenes and alkynes are unsaturated. What does it mean?
Answer. Unsaturated molecules have carbon carbon double bonds or triple bonds. Alkenes and alkynes contain double or triple bond between carbon atoms, hence they are unsaturated. Unsaturated molecules are those in which more atoms can be added.(They undergo addition reaction)
Question. A and B are two organic compounds with the same molecular formula C5H10.
Write their names and structural formulae in case
(a) A is a cyclic compound.
(b) B is a straight chain compound.
(c) Among A and B, which one will have only single bonds?
(d) Will it be A or B that has both single and double bonds?
(Note: the double bond can be between any 2 of the 5 carbon atoms)
(c) A (Cyclopentane).
(d) B (Pentene)
Question. Why does carbon form compounds mainly by covalent bonding?
Answer. Carbon atoms have 4 valence electrons in their valence shell, it needs to gain or lose 4 electrons to attain the noble gas configuration.
(i) It could gain four electrons forming C4- anion. But it would be difficult for the nucleus with six protons to hold on to ten electrons.
(ii) It could lose four electrons forming C4+ cation. But it would require a large amount of energy to remove four electrons from its outermost shell. Therefore, carbon shares its valence electrons to complete its octet with other atoms to form covalent bonds.
Question. List the common physical properties of carbon compounds.
Answer. They have covalent bonds between their atoms therefore they do not form ions. So they are poor conductors of electric current. These compounds have low melting and low boiling points. They are generally insoluble in water but soluble in the organic solvents like ether, carbon- tetrachloride, etc.
Question. (a) State two characteristic features of carbon which when put together give rise to a large number of carbon compounds.
(b) Catenation is the ability of an atom to form bonds with other atoms of the Same element. It is exhibited by both carbon and silicon. Compare the ability Of catenation of the two elements. Give reasons.
Answer. (a) The size of carbon atom is very small (Atomic radius = 77 pm) The strength C—C bond is quite high (355 kJ mol-1) Therefore, any number of carbon atoms can be linked by covalent bonds, This self-linking property is called catenation.
(b) Carbon shows catenation to large extent as compared to silicon as well as any other element due to smaller size of carbon. C—C bond is stronger than Si-Si bond because Si is larger in size, forms weaker bond.
Question. Identify the following-
(i) An allotrope of carbon which has a two-dimensional layered structure consisting of flat hexagonal rings.
(ii) An allotrope of carbon which looks like a soccer ball.
(iii) An allotrope of carbon which contains both single and double bonds.
Answer. (i) Graphite (ii) Buckminsterfullerene (iii) Graphite