Selina Concise Class 8 Chemistry Solution Chapter No. 9- ‘Carbon and it’s Compound’ For ICSE Board Students.
1) a) .…………..is present in both living and non living things.
Answer : Carbon
Explanation: Carbon is present in both living and non living things carbon present in some living things ( Humans , plants, insect, etc) called organic carbon , and carbon present in non living things ( rock, pen, building etc ) are called inorganic carbon.)
b) The tendency of an element to exist in two or more forms but in the same physical state is called ………………
Answer : Allotropy
Explanation: The elements have different form , properties , but same physical state known as Allotropy.
c) ………….. and ………….. are the two major crystalline allotropes of carbon.
Answer : Crystalline and Non crystalline
Explanation: Crystalline allotropes are the homogeneous mixture of atom or elements in which particles are arranged in definite order, and non crystalline allotropes of carbon are the irregular arrangements of particles , which is Heterogeneous mixture .
d) ………….. is the hardest substance that occur naturally.
Answer : Diamond
Explanation: Diamond is the hardest substance, outermost four electrons of carbon atom shared electrons with four electrons of carbon atoms and make very strong bond (extremely rigid tetrahedral crystal ) so due to this strong arrangements of molecules diamond become hardest substance.
e) The name carbon is derived from a Latin word …………….
Answer : Carbo
Explanation: Carbon is derived from Latin word carbo , the meaning of carbo is coal.
2) a)
Answer : iv) Petroleum :
(Combined state of carbonoccur as petroleum which is consistent of hydrocarbons )
b)
Answer : iii) Sugar
(The crystalline form of carbon is a sugar , in which carbon atoms are covalently bonded to each other)
c)
Answer : ii) Maharashtra
(Graphite is not found in Maharashtra )
d)
Answer : iii) cutting and drilling rocks and glass
( Diamond is used for cutting and drilling rocks and glass)
e)
Answer : Carbon atoms can form long chain
(Carbon forms innumerable compounds because carbon atoms can form long chain)
3) a)
Answer : True
b)
Answer : False
c)
Answer : False
d)
Answer : True
e)
Answer : True .
4)
a)
Answer : Allotropy:
The elements have different form , properties , but same physical state known as Allotropy.
b)
Answer : Carat :
A unit of weight for measuring Precious things like , diamond gold etc .
c)
Answer : Crystal :
Homogeneous solid mixture in which atoms or molecules are placed in definite order and this solid have definite geometrical shaped know as crystal .
d)
Answer : Catenation :
The bonding of identical atoms to form long chain, like branches structure , cyclic structure are known as catenation.
5) a)
Answer: Crystal :- Crystal is a substance whose atom or molecules are arranged in a definite pattern.
b)
Answer: Allotropy:-Allotropy is a different form of an element found in the same physical state.
c)
Answer: Catenation :-The property by which atom of an element link together to form long chain or ring compound .
6) a)
Answer : Diamond
b)
Answer : Graphite
c)
Answer : Fullerenes
7) a)
Answer : Graphite is a good conductor of electricity but not diamond because graphite have delocalised or free electrons that’s why graphite is good conductor of electricitybut indiamond not having free electrons , all four electrons present outermost orbit of carbon atom used for making covalent bond that’s why diamond is bad conductor of electricity.
b)
Answer : diamond is very hard because outermost four electrons of carbon atom shared electrons with four electrons of carbon atoms and make very strong bond (extremely rigid tetrahedral crystal ) so due to this strong arrangements of molecules diamond become hardest substance.
c)
Answer : Fullerenes consists of carbon atom which is connected to each other with single and double bond to form spherical cage like structure or Bucky balls shape . Most common Fullerenes are Buckminster or Bucky- ball.
d)
Answer : Copper oxide as a impurity present in black diamond.
8) a)
Answer : Graphite :
- Graphite used for making electronic products like electrodes , batteries , solar panel.
- Graphite is used form making pencil lead.
- Graphite used for making lubricant.
- It is used for making black paint and ink.
b)
Answer : Diamond :
- Diamond is lustrous property due to this diamond used for Jewellery as a gem.
- Diamond is hardest substance due to this diamond is used for cutting or drilling of rocks and glass .
- Diamond also used for industrial purpose.
9).
Answer :
Sr.No. | Graphite | Diamond |
1 | Graphite is a black and opaque substance | Pure diamond is transparent. |
2 | Graphite is soft and slippery to touch. | Diamond is hardest substance. |
3 | Graphite is good conductor of electricity. | Diamond is poor conductor of electricity. |
4 | Density of graphite is less than diamond. | Density of diamond is more than graphite. |
5 | It occurs as octahedral crystals. | It occurs as hexagonal crystals. |