1580
J S Tutorial
Class 10
| Chemistry: Carbon and its Compounds | Full marks: 40 | Time: 1 hr
Section A: Questions
1 to 8 carry 1 mark each
|
1. Which
element is the basis of organic chemistry? a. Oxygen b. Carbon c. Hydrogen d. Nitrogen |
2. How many
valence electrons does carbon have? a. 2 b. 4 c. 6 d. 8 |
|
3. What is the
general formula of an alkane? a. CnH2n+2 b. CnH2n c. CnH2n-2 d. CnH2n+1 |
4. Ethene is an
example of a: a. Saturated hydrocarbon b. Unsaturated hydrocarbon c. Alkane d. Aromatic compound |
|
5. Which of the
following compounds is an unsaturated hydrocarbon? a. Methane b. Ethane c. Ethene d. Propane |
6. The bond
formed when two carbon atoms share two pairs of electrons is called: a. Single bond b. Double bond c. Triple bond d. Coordinate bond |
|
7. Which of the
following is an example of a functional group in organic compounds? a. OH (Hydroxyl) b. H2O (Water) c. CO2 (Carbon dioxide) d. NaCl (Sodium chloride) |
8. Which of the
following is a homologous series of hydrocarbons? a. Alkali metals b. Alkenes c. Non metals d. Hallides |
|
9. Alkanes are
unsaturated hydrocarbons. a. True b. False |
10. Isomers
have the same molecular formula but different structural arrangements. a. True b. False |
|
11. Ethanol is
an example of an alkane. a. True b. False |
12. Alkynes
have a triple bond between carbon atoms. a. True b. False |
Section B: Fill in the Blanks (1
Marks Each)
13. The process
in which a substance reacts with oxygen gas, releasing energy in the form of
light and heat, is called ___________________________.
14.
Define Isomerism.
15.
Write the molecular formula of methane.
16.
Name the process used for the conversion of
vegetable oils to vegetable ghee.
17.
What is the chemical name of CH3OH?
18.
Why is the alkane series known as the 'saturated
hydrocarbons'?
19.
What is the structural formula of ethene?
20.
What is the functional group of aldehydes?
Section C: (2 Marks Each)
21. Write
the chemical equation for the combustion of methane.
22.
Explain why carbon compounds are generally poor
conductors of electricity.
Section D:
Short Answer Questions (3 Marks Each)
23.
Give two examples of functional groups found in
organic compounds and describe their characteristics.
24.
Differentiate between saturated and unsaturated
hydrocarbons, providing an example of each.
Section E: Long Answer Questions
(5 Marks Each)
25. Describe
the structure and properties of carbon atoms, highlighting its ability to form
different types of bonds.
26.
Explain the significance of the homologous
series in organic chemistry, giving examples of compounds from the same series.
**Answers**
1. b. Carbon
2. b. 4
3. a. CnH2n+2
4. b. Unsaturated hydrocarbon
5. c. Ethene
6. b. Double bond
7. a. OH (Hydroxyl)
8. b. Alkenes
9. False
10. True
11. False
12. True
13. Combustion Reaction
14. Isomerism is the phenomenon where two or more compounds
have the same molecular formula but different structural or spatial
arrangements.
15. CH4.
16. Hydrogenation.
17. Methanol.
18. The alkanes series is known as 'saturated hydrocarbons'
because they contain only single covalent bonds between carbon atoms and are
saturated with hydrogen.
19. H2C=CH2.
20. -CHO
21. CH4 + 2O2 → CO2 + 2H2O
22. Carbon compounds are generally poor conductors of
electricity because they do not contain free ions or electrons.
23. Functional groups are specific groups of atoms within
organic compounds that determine the compound's chemical properties and
reactivity. Here are two examples:
1. Hydroxyl Group (–OH):
-
The hydroxyl group consists of an oxygen atom
bonded to a hydrogen atom and attached to a carbon atom in an organic molecule.
-
It imparts hydrophilic (water-attracting)
properties to the molecule, making it more likely to form hydrogen bonds with
water.
-
Compounds containing the hydroxyl group are
called alcohols. They often have properties like solubility in water and can
participate in hydrogen bonding, which affects their physical and chemical
properties.
2. Carboxyl Group (–COOH):
-
The carboxyl group consists of a carbonyl group
(C=O) and a hydroxyl group (–OH) bonded to the same carbon atom.
-
It imparts acidic properties to the compound, as
it can release a proton (H⁺) to function as a weak acid.
-
Carboxyl groups are characteristic of carboxylic
acids and are essential for the acidic nature of these compounds.
24.
|
Characteristic |
Saturated
Hydrocarbons |
Unsaturated
Hydrocarbons |
|
Type of Carbon-Carbon Bonds |
Single covalent bonds (C-C) |
Double or triple covalent bonds (C=C or C≡C) |
|
Degree of Hydrogen Saturation |
High (maximum number of hydrogen atoms per carbon atom) |
Low (fewer hydrogen atoms per carbon atom) |
|
Chemical Reactivity |
Relatively low reactivity due to the absence of multiple
bonds |
Relatively high reactivity due to the presence of
multiple bonds |
|
Stability |
More stable |
Less stable |
|
General Formula |
CnH2n+2 (for alkanes) |
CnH2n (for alkenes) or CnH2n-2 (for alkynes) |
|
Example |
Alkane: Methane (CH4) |
Alkene: Ethene (C2H4) |
25. Carbon is a versatile element with a unique ability to
form a wide variety of chemical bonds, which contributes to its significance in
the diversity and complexity of organic compounds.
Structure of Carbon Atom:
·
Carbon is a non-metal element with an atomic
number of 6, which means it has six protons in its nucleus and six electrons
orbiting the nucleus.
·
In its ground state, a carbon atom has two
electrons in its innermost shell and four valence electrons in the second shell.
·
The electron configuration of carbon is 2,4
indicating that it has four valence electrons available for bonding.
Properties:
·
Carbon is a relatively small and light atom, and
its small atomic size allows for the formation of strong covalent bonds.
·
Carbon-carbon bonds are stable and can exist in
various forms (single, double, or triple), contributing to the diversity of
organic compounds.
·
Carbon-carbon single bonds are flexible and can
rotate, leading to the structural versatility of organic molecules.
·
Carbon's ability to form stable covalent bonds
with other nonmetals like hydrogen, oxygen, nitrogen, and halogens results in a
vast array of organic compounds with different functional groups and
properties.
·
Carbon-based compounds (organic compounds) are
essential for life, as they form the basis of all living organisms and many
synthetic materials.
Bonding Capabilities:
1. Covalent Bonds: Carbon primarily forms covalent bonds,
where it shares electrons with other atoms to achieve a stable electron
configuration. Carbon can form both single, double, and triple covalent bonds.
· a. Single Bonds: In a single covalent bond,
two carbon atoms share one pair of electrons. For example, in a
molecule like methane (CH4), carbon forms four single covalent bonds with four
hydrogen atoms.
· b. Double Bonds: In a double covalent
bond, two carbon atoms share two pairs of electrons. This is seen in molecules like ethene (C2H4),
where carbon-carbon double bonds exist.
· c. Triple Bonds: In a
triple covalent bond, two carbon atoms share three pairs of electrons. This is exemplified in
molecules like ethyne (C2H2).
2. Hydrogen Bonds: Carbon can also form hydrogen bonds with
hydrogen atoms when it is part of a molecule with electronegative atoms like
oxygen, nitrogen, or fluorine. These hydrogen bonds are important for the
structure and stability of various organic compounds.
26. A homologous series is a group of organic compounds with
a similar structural feature, and each member of the series differs from the
next by a constant increment, typically a CH2 unit. This concept is important
for the following reasons:
a)
Predictability: Compounds within a
homologous series have predictable properties and chemical reactivity. This
predictability is based on the consistent change in structure as you move from
one member to the next. For example, each member of the alkane series (saturated
hydrocarbons) has a general formula of CnH2n+2, and you can predict the
physical and chemical properties of each alkane by knowing its molecular
formula.
b)
Gradual Change: The gradual change
in the number of carbon atoms in the structure results in a systematic
variation in properties. For instance, as you move from one alkane to the next
in the homologous series (e.g., methane, ethane, propane, butane), you observe
a gradual increase in boiling point, melting point, and molecular weight.
c)
Isomerism: Members of a homologous series
often exhibit structural isomerism, where different compounds within the series
have the same molecular formula but different arrangements of atoms. This
isomeric diversity within a series leads to compounds with unique properties
and applications. For example, butane (C4H10) has two isomers: n-butane and
isobutane.
d)
Generalization: The characteristics of a
particular functional group or structural feature can often be generalized
based on the homologous series to which a compound belongs. This makes it
easier to study and understand the properties of many related compounds.
e)
Nomenclature: The systematic nomenclature
of organic compounds is facilitated by the concept of homologous series. For
instance, the IUPAC naming rules for alkanes follow a systematic pattern based
on the number of carbon atoms, making it easier to name and identify compounds.
Examples of homologous series and compounds from each
series:
1. Alkanes: Saturated
hydrocarbons with single carbon-carbon bonds.
- Examples: Methane (CH4), Ethane (C2H6), Propane (C3H8), Butane
(C4H10).
2. Alkenes: Hydrocarbons
with at least one carbon-carbon double bond.
- Examples: Ethene (C2H4), Propene (C3H6), Butene (C4H8).
3. Alkynes: Hydrocarbons
with at least one carbon-carbon triple bond.
- Examples: Ethyne (C2H2), Propyne (C3H4), Butyne (C4H6).
4. Alcohols: Compounds
containing the hydroxyl group (–OH).
- Examples: Methanol (CH3OH), Ethanol (C2H5OH), Propanol (C3H7OH).
5. Carboxylic Acids:
Compounds containing the carboxyl group (–COOH).
- Examples: Formic acid (HCOOH), Acetic acid (CH3COOH), Propionic acid
(C2H5COOH).
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