All CBSE class 10 aspirants waiting for CBSE II term Class 10 Science 2022 sample question paper, so here you are provided the same. These questions are based on the new pattern of CBSE board exams 2022.
Syllabus
for II Term Science Class 10 – 40 marks
1.
Carbon
and its compounds
2.
Periodic
Classification of Elements
3.
How
Do Organisms Reproduce?
4.
Heredity
and Evolution
5.
Electricity
6.
Magnetic
Effect of Electric Current
7.
Our
Environment
Practice Questions of Chapter 04 Carbon and Its Compounds
These questions
are based on NCERT Solutions of class 10 science chapter 4, so before you go
through these practice questions, you must read the solutions of chapter 4.
Multiple Choice Questions:
1. Carbon
exists in the atmosphere in the form of
(a)
only carbon monoxide
(b)
carbon monoxide in traces and carbon dioxide
(c)
only carbon dioxide
(d) coal
Solution - (c) Carbon exists in the atmosphere in the form of carbon dioxide gas (CO2) in the air (only 0.03%). Carbon also occurs in the earth’s crust in the form of minerals like carbonates. It also occurs in the form of fossil fuels, organic compounds, wood, cotton, and wool, etc.
2. Which
of the following will contain a covalent double bond between its atoms?
(a)
CO2
(b) O2
(c)
NaCl
(d)
Cl2
Solution - (b) Oxygen atom has six (6) valence electrons. Thus, to complete its octet, it forms a double bond with another oxygen atom to get O2 molecule.
3. The
name of the compound CH3-CH2-CHO is
(a)
propanone
(b)
propanal
(c)
ethanol
(d)
ehanal
Solution - (b)
4. A
molecule of ammonia (NH3) has
(a)
only single bonds
(b)
only double bonds
(c)
only triple bonds
(d)
two double bonds and one single bond
Solution - (a) A molecule of ammonia (NH3) has only single bonds and these are covalent bonds.
5. The
structure of S8 molecule is ....... shaped.
(a)
ring
(b)
crown
(c)
circle
(d)
rectangle
Solution -(b) 8 covalent bonds are formed in S molecule.
6. Which
of the following is not the use of graphite?
(a)
It is used as a lubricant
(b)
It is used in the manufacturing of lead-pencils
(c)
It is used in the manufacturing of artificial diamond
(d)
It is used for making insulated plates
Solution - (d) Graphite cannot be used for making insulated plates, because it is a good conductor of electricity. In graphite, each carbon has a free electron.
7. Which
of the following elements does not show tetravalency?
(a)
Ge
(b)
Si
(c)
C
(d)
O
Solution - Elements Ge, Si, and C belongs to group 14 and show tetravalency but oxygen show valency 2 so it does not show tetravalency.
8. .......
is the first synthesized organic compound.
(a)
Alcohol
(b)
Vinegar
(c) Urea
(d)
Benzene
Solution - (c) urea – This compound was first prepared by Friedrich Wohler .
9. Carbon
can use four hydrogen atoms to form methane (CH4). because
(a)
valency of carbon is four
(b)
valency of hydrogen is one
(c) both (a) and (b)
(d)
carbon gets noble gas configuration by making four covalent bonds with hydrogen
Solution - (c) Carbon has four free electrons so it share these electrons with four hydrogen atoms to form methane.
10. Pentane has the molecular
formula C5H12. It has
(a)
5 covalent bonds
(b)
12 covalent bonds
(c)
16 covalent bonds
(d)
17 covalent bonds
Solution - (c) It contains 16 covalent bonds.
11. Match the following :
|
Column
I |
Column
II |
|
A. C3H8 |
(i) Cyclic compound |
|
B. C6H6 |
(ii) Alkyne |
|
C. C2H2 |
(iii) Alkene
|
|
D. C4H8 |
(iv) Alkane
|
|
|
|
12. Carbon forms four
covalent bonds by sharing its four valence electrons with four univalent atoms
eg. Hydrogen. After the formation of four bonds carbon attains the electronic
configuration of
(a)
neon
(b)
helium
(c)
argon
(d)
krypton
Solution - (a)
13. Oil on treating with hydrogen in the presence of palladium or
nickel catalyst form fats, this is the reaction of?
(a)
substitution reaction
(b)
addition reaction
(c)
oxidation reaction
(d)
displacement reaction
Solution -(b) oil has fatty acid which are unsaturated hydrocarbons , so hydrogen is added to form saturated hydrocarbons. This is addition reaction.
14. Alcohol can be produced
by the hydration of
(a)
alkynes
(b)
acids
(c)
alkenes
(d)
alkanes
Solution -(c) on hydration of alkenes
15. The general formula of esters where ‘R’ represents the alkyl group is?
(a)
RCOOH
(b)
ROH
(c)
RCOOR
(d)
RCOR
Solution -(c) RCOOR
Assertion – Reasoning MCQs
Direction: (Q. Nos. 16-20) Each of these questions contains two statements Assertion (A) and Reason (R). Each of these questions also has four alternative choices, any one of which is the correct answer. You have to select one of the codes (a), (b), (c) and (d) 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.
16. Assertion- Carbon and its compounds are used as fuel for most appliances.
Reason- On the combustion of carbon, a large amount of heat and light is released.
Solution -(a) carbon and its compounds are used as fuels because on combustion, they produce heat and light in large amount.
17. Assertion -Diamond does not conduct electricity.
Reason- Diamond has a high refractive index.
Solution - (c) diamond does not conduct electricity because carbon in diamond does not have free electron.
18. Assertion- Graphite is slippery to touch.
Reason -The various layers of carbon atoms in graphite are held together by weak van der Waals forces
Solution -(a) in graphite, carbon atoms joined to form hexagonal rings which are further combined to form layers. Each layer connected with other layer by a weak Van der waal’s forces so both (a) and(b) are correct
19. Assertion- carbon shows maximum catenation property in the periodic table.
Reason- Carbon has a small size and thus, forms a strong C – C bond.
Solution - (a) Catenation of bonding of atoms of the same element into a series so R is the correct explanation of A.
20. Assertion -Graphite is slippery to touch:
Reason – The various layers of carbon atoms in graphite are held together by weak van der Waal's forces.
Solution - (a) Both A and R are correct. Candle flame is yellow due to the presence of unburnt carbon particles when light fall on these particles, they scatter yellow colour. This show the combustion of hydrocarbons in wax is not complete.
Case-Based MCQs
21. Read the following and answer the questions from (i) to (v) given below
Most of the carbon compounds are poor conductors of electricity. The bonds which are formed by the sharing of an electron pair between the atoms(atoms may be the same or different) are known as covalent bonds.
As neutral atom carbon has electronic configuration KL (2,4). It has four electrons in the outermost shell. To gain inert gas configuration carbon can either donate 4 valence electrons or gain 4 electrons, but it cannot do so. To acquire inert gas configuration carbon can only share its 4 valence electrons with other atoms forming covalent bonds. The concept of covalent bonds was given by Langmuir and Lewis to explain bonding in non-ionic compounds. The covalent bonds are of three types. If each atom contributes one electron, the covalent bond formed is called a single covalent bond and is represented by a single line (-) and if each atom contributes two electrons, the covalent bond formed is called a double bond and is represented by a double line (eq.) and if each atom contributes three electrons, the covalent bond formed is called a triple bond and is represented by a triple line (≡).
The electrons in a covalent bond are simultaneously attracted by the two atomic nuclei. A covalent bond forms when the difference between the electro-negativities of transfer occurs to form ions.
(i) N2 has ……………bond in between two nitrogen atoms?
(a) single covalent bond
(b) double covalent bond
(c) Ionic bond
(d) triple covalent bond
Solution -(d)
(ii) Which of the following contains a double bond?
(a) O2
(b) N2
(c) CH4
(d) H2
Solution - (a)
(iii) The electronic configuration of chlorine is 2,8,7. How many pairs of electrons are shared by chlorine to form Cl2
(a) one pair
(b) two pair
(c) three pair
(d)none
Solution -(a)
(iv) What is the covalency of nitrogen?
(a) 1
(b) 2
(c) 3
(d) 4
Solution - (c)
(v) The shared pair of electrons is said to constitute a ............. bond between two oxygen atoms.
(a) single
(b) double
(c) triple
(d) ionic
Solution -(b)
22. Read the following and answer the questions from (i) to (v) given below
Allotropy is the property by virtue of which elements exist in more than one form and these different forms of an element are called allotropes.
Allotropy has similar chemical properties but they differ in their physical properties. Carbon exists in crystalline and amorphous.
In crystalline form, it occurs as diamond, graphite, and fullerenes. Diamond is a colorless, transparent substance having extraordinary brilliance. It is the hardest natural substance known. It is used for cutting marble, granite, and glass. Graphite is a greyish-black opaque substance. It is lighter than diamond, i.e. it has a lower density. It has a sheet-like structure having hexagonal layers.
One layer slides over the other layer which makes it soft to touch. It is the reason that graphite is used as a lubricant. The amorphous form of carbon is also known as a micro-crystalline form which consists of coal, lampblack, and charcoal.
(i) The compound ‘X’ is the conductor of electricity. It has the following structure. Name the compound
(a) coal
(b) graphite
(c) fullerene
(d) diamond
Solution -(b)- Graphite has ring-shaped layered structure and due to free electrons , it is conductor of electricity
(ii) Which of the following is correct about the structure of diamond?
(a) Carbon atoms conduct electricity in the molten state
(b) Carbon atoms are held together by single covalent bonds.
(c) Electrons are freely through the structure
(d) Layers of atoms slide easily over each other
Solution - (b)
(iii) Which three allotropes of carbon, do the given figure represents? Figure
I II III
(a) Diamond Graphite Buckminster fullerene
(b) Graphite Buckminster fullerene Diamond
(c) Diamond Buckminster fullerene Graphite
(d) Graphite Diamond Buckminster fullerene
Solution - (a)
(iv) Identify the incorrect statement (s).
i. Diamond is the hardest substance known while graphite is smooth and slippery.
ii. Diamond is made up of billions of carbon atoms.
iii. Graphite is a poor conductor of electricity, unlike other non-metals.
iv. Graphite has a giant covalent structure that is made up of layers of carbon atoms. In each layer, each carbon atom is bonded to three other carbon atoms to form hexagonal rings of carbon atoms.
(a) i and ii
(b) only iii
(c) ii and iv
(d) i, ii, and iv
solution - (b) Graphite is a good conductor of electricity.
(v) Which covalent compound is soluble in water?
(a) sugar
(b) ethane
(c) chlorine
(d) methane
Solution - (a)
Part 2 - Subjective Questions:
Short Answer Type Questions:
1. What
do you mean by covalent bonding?
Solution - Carbon shares it’s valence electrons with another atom to attain the nearest noble gas configuration. This type of bonding is called covalent bonding.
2. Explain
the nature of the covalent bond using the bond formation in CH2Cl2.
Solution- The bonds that are formed by sharing electrons are known as a covalent bond. In covalent bonding, both atoms share the valence electrons, i.e. the shared electrons belong to the valence shells of both the atoms. CH2Cl2 is called dichloromethane, which contains 1 carbon atom, 2 hydrogen atoms and 2 chlorine atom.
3. What
would be the electron dot structure of ammonia which has molecular formula NH3
?
Solution - Atomic number of N = 7
Electronic configuration = 2,5
Atomic number of H = 1
Electronic configuration = 1
To attain the stable electronic configuration, Nitrogen
needs 3 electrons, while each hydrogen needs 1 electron. So, in NH3, the nitrogen atom shares three electrons with three hydrogen atoms Thus, nitrogen and hydrogen both complete their octet.
4. (i)
Explain the formation of calcium chloride with the help of electron dot
structure.
(Atomic numbers of Ca = 20; Cl =17)
Solution - The formation of calcium chloride with the help of electron dot structure.
Two valence electrons of calcium are shared with the valency of two chlorine to
attain the noble gas configuration.
(ii) Why do ionic compounds not conduct electricity in the solid-state but conduct electricity in a molten and aqueous state?
Solution - Ionic compounds do not conduct electricity in a solid-state because, in a solid-state, there is no free ion to move and pass electricity. But in the molten and aqueous state, there is free ions to move and pass electricity.
5. Carbon
a group (14) element in the periodic table, is known to form compounds with
many elements. Write an example of a compound formed with
(i) chlorine (group 17 of the periodic table)
(ii)
Oxygen (group 16 of the periodic table)
solution (i) - 1. (i) Electronic configuration of carbon -2,4
Electronic configuration of chlorine – 2, 8 ,7
carbon needs 4 electrons to attain the electronic
configuration of the nearest noble gas, and chlorine needs 1 electron. So, with
chlorine, carbon forms carbon tetrachloride. Electron dot structure and
structural formula of CCl4
Solution- Electronic configuration of oxygen – 2,6
Electronic configuration of carbon – 2,4
Carbon needs 4 electronics and oxygen needs 2 electrons to attain the electronic configuration of the nearest noble gas.
each oxygen atom shares 2 electrons with carbon to
form carbon dioxide.
6. State
the valency of each carbon atom in
(i) an alkane and (ii) an alkene
Solution - (i) Valency of each carbon atom in an alkane is four.
(ii) Valency of each carbon atom in an alkyne is four.
7. Covalent
compounds are generally poor conductors of electricity. Explain why?
Solution - Covalent compounds are formed by sharing of electrons and they don't have free electrons so they are poor conductors of electricity.
8. Why does a diamond have a high
melting point?
Solution - Diamond consists of carbon atoms in which each carbon atom is bonded to four other carbon atoms forming a rigid three-dimensional structure, that's why diamond is very hard and so a lot of energy is needed to break the strong covalent bond, that's why it has a high melting point.
9. What are the main key factors
that enable carbon to form a large number of compounds?
Solution - Following are the main factors that enable carbon to form a large number of compounds are
(i)Catenation- carbon has the tendency to form long and branched chains, which is known as catenation. Carbon forms long chains by combining with
other carbon atoms through covalent bonds.
(ii) Tetravalency- carbon has 4
valence electrons, so it can form 4 covalent bonds with four different atoms,
or two double bonds or a single and a triple bond with other atoms.
(iii) Carbon forms strong bonds with most other elements like H, O, N, S, Cl, etc.,
due to its small size which helps it to attract more electrons.
10. Why covalent compounds are volatile in nature with low boiling and low melting point?
Solution -Covalent compounds have low melting and boiling points due to small intermolecular forces of attraction between the atoms.
11. Diamond is a poor conductor of electricity while graphite is a good conductor. Assign reason.
Solution - In diamond, each carbon atom shares four electrons with the other carbon atoms so there is no free electron to conduct electricity.
Whereas in graphite, each carbon atom shares three electrons with other carbon atoms and the fourth electrons remain free so graphite is a good conductor of electricity.
12. What will be the structural formula of cyclehexane?
Solution - structural formula of cyclohexane
13. Answer the following:
(i) Carbon is a versatile
element. Give reason.
(ii)Explain the structural
difference between saturated and unsaturated hydrocarbons with two examples
each.
(iii)What
is a functional group? Write examples of four different functional groups.
Solution - (i) Carbon shows the property of catenation due to which it forms a large number of compounds. Carbon is tetravalent. Due to this, it forms covalent compounds only.
(ii) Saturated hydrocarbons contain carbon-carbon single bonds. e.g. methane (CH4), ethane (C2H6). Unsaturated hydrocarbons contain at least one carbon-carbon double or triple bond. e.g. Propene (C4H8), butyne (C3H4).
(iii) Functional group is an atom or group of atoms
joined in a specific manner that is responsible for the chemical properties of the organic compounds.
Examples - aldehyde group (-CHO), alcohols (-OH), carboxylic group (-COOH), ketone (-CO), etc.
14. Select saturated
hydrocarbons from the following:
C3H6; C5H10; C4H10; C2H4; C6H14
Solution -Saturated hydrocarbon are those compounds that have single bond among all the carbons present in them.They belongs to formula CnH2n + n.
C4H10; C6H14
15. Write the molecular
formula of the following compounds and draw their electron dot structures
(i) Ethane (ii) Ethene
Solution - (i)
Molecular formula of ethane is C2H6. Its electron dot
structure is
(ii) Molecular formula of ethene is C2H4. Its electron dot structure is
16. Why is the conversion of ethanol to ethanoic acid an oxidation reaction?
Solution- The conversion of ehtanol to ethanoic acid is given in the following reaction-
C2H5OH + O2 → CH3COOH + H2O
Ethanol contains one atom of oxygen and that of acetic acid contains two atoms of oxygen.
Oxidation is addition of oxygen to a substance so the conversion of ethanol to ethanoic acid is an oxidation.
17 .Why does micelle formation take place when soap is added to water? will micelle be formed in other solvents such as ethanol ?
Solution - There are two ends of a soap molecule which have different properties , one end is polar in nature (hydrophilic end) soluble in water where as the other end is non- polar (hydrophobic end) insoluble in water.
On addition of saop of water , the polar end gets dissolve in water while the non- polar end does not , due to this micelles are produced . As soap is soluble in ehtanol ,so micelle formation does not occur.
18. A salt X is formed and a gas is evolved when ehanoic acid reacts with sodium hydrogen carbonate. name the salt X and the gas evolved. Describe an activity and draw the diagram of the apparatus to p[rove that the evolved gas is the one which you have named.Write the chemical reaction.
Solution- CH3COOH + NaHCO3 → CH3COONa + H2O + CO2
The compound X is sodium acetate or sodium ehtanoate and gas evolved is carbondioxide according to activity that lime water turns milky when this gas is passesd through , so the gas is carbondioxide.
19. Describe the properties
of graphite.
Solution -
20.Why is homologous series
of carbon compounds so called? Write the chemical formula of two consecutive
members of any homologous series and state the part of these compounds that determines
their (i) physical and (ii) chemical properties.
21. Write the next higher
order homologous of CH2O, C2H2 and C2H5
COOH.
Long Answer Type Questions:
22. State the reason why
carbon can neither form C4+ cations nor C4- anions but
forms a covalent compound. Also, state reasons to explain why covalent compounds.
(i)
Are bad conductors of electricity?
(ii)
Have low melting and
boiling point?
23. Explain the formation of
oxygen (O2) molecule and sulphur (S8) molecule.
24. Why organic compounds are
called as hydrocarbons? Write the general formula for homologous series of
alkanes, alkenes and alkynes and also draw the structure of the first members
of each series.
25. Explain the nature of the
covalent bond using the bond formation is CH3Cl
26. What are covalent
compounds? Why are they different from ionic compounds? List their three
characteristics properties.
Case-based Questions:
27. Read the following and
answers the questions from (i) to (v) given below
Compounds that contain only carbon and hydrogen are
called hydrocarbons. Among these, the compounds containing all single covalent bonds
are called saturated hydrocarbons while the compounds containing at least one
double or triple bond are called unsaturated hydrocarbons.
Saturated hydrocarbons after combustion give a clean
flame while unsaturated hydrocarbons gave a yellow sooty flame. Unsaturated
hydrocarbons are more reactive than saturated hydrocarbons.
Unsaturated hydrocarbons add hydrogen in the presence
of catalysts such as palladium or nickel to give saturated hydrocarbons.
Study the table related to three hydrocarbons A, B, C
and answer the questions that follow
|
Organic compound |
Molecular formula |
|
A |
C4H10 |
|
B |
C5H10 |
|
C |
C4H6 |
(i) What is the name of compound A?
(ii) Write two differences between saturated
and unsaturated hydrocarbons.
(iii) In
unsaturated compounds, what is the minimum number of carbon atoms and why?
(iv) Among
compounds A, B, and C, which of the following is a saturated hydrocarbon?
(v) Compound C belongs to which category of
hydrocarbon and what is its general formula?
28. Read the following and
answer the questions from (i) to (v) given below:
Organic compounds with the same molecular formula but
different chemical and physical properties are called isomers. This phenomenon
is called isomerism.
When the isomerism is due to differences in the arrangement
of atoms within the molecule, without any reference to space, the phenomenon is
called structural isomerism. In other words, structural isomers are compounds
that have the same molecular formula but different structural formulas, i.e.
they are different in the order in which different atoms are linked or they
have different connectivities depending upon the order they are put together.
In these compounds, carbon atoms can be linked together In these compounds,
carbon atoms can be linked together in the form of straight-chain, branched
chains or even rings.
(i)Name any set of compounds
that have the same molecular formula but different structural formula.
(ii) Which property of carbon
leads to the formation of branched chains?
(iii) How
many isomers of pentane are possible?
(iv) Name
two compounds that contain six carbon atoms and have a cyclic structure.
(v) What is the minimum
number of carbon atoms required to form an isomer?
29. Read the following and
answer the questions from (i) to (v)
given below :
Hydrocarbons are the simplest organic compounds and
are regarded as parent organic compounds. All other compounds are considered to
be derived from them by the replacement of one or more hydrogen atoms by other
atoms or groups of atoms.
Functional groups
are an atom or groups of atoms that make a carbon compound (or organic
compound) reactive and decide its properties. 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 two consecutive members of series differ by the same general
formula and two consecutive members of series differ by – CH2 group
in their molecular formula is called a homologous series.
CH4,
C2H4, C2H6 , C3H6 , C3H8
(i)
Which compound belongs to the same homologous series?
(ii)
What is the functional
group of compound Ethanal?
(iii) Compound
Propane belongs to which homologous series?
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