Samacheer Kalvi Class 8 Science Unit 15 Chemistry in Everyday Life Solutions
Welcome to NCTB Solutions. Here with this post we are going to help 8th class students by providing Solutions for Samacheer Kalvi Class 8 Science Unit 15 Chemistry in Everyday Life. Here students can easily find all the solved solution for Chemistry in Everyday Life Exercise questions. Also here our Expert Science Teacher’s solved all the questions with easily understandable language with proper guidance so that all the students can understand easily. Here on this post students will get Unit 15 Chemistry in Everyday Life exercise solutions. Here all the solutions are based on Tamil Nadu State Board latest syllabus.
Unit 15 Chemistry in Everyday Life Exercise Questions Solutions :
(I) Choose the best answer
(1) The chemical mixed with LPG that helps in the detection of its leakage is ___
(a) methanol
(b) ethanol
(c) camphor
(d) mercapton
Answer :
Correct Option → (d)
The chemical mixed with LPG that helps in the detection of its lekage is Mercapton.
(2) Which is known as syn gas?
(a) Marsh gas
(b) Water gas
(c) Producer gas
(d) Coal gas
Answer :
Correct Option → (b)
Water gas is known as syngas.
(3) The unit of calorific value of fuel is __
(a) KJmol-1
(b) KJg-1
(c) KJkg-1
(d) Jkg-1
Answer :
Correct Option → (c)
The unit of calorific value of fuel is KJKg-1.
(4) __ is the coal of superior quality.
(a) Peat
(b) Lignite
(c) Bituminous
(d) Anthracite
Answer :
Correct Option → (d)
Anthracite is the coal of superior quality.
(5) The main component of natural gas is __
(a) methane
(b) ethane
(c) propane
(d) butane
Answer :
Correct Option → (a)
The main component of natural gas is Methane.
(II) Fill in the blanks
(1) Producer gas is a mixture of ___ and ___
(2) ___ is known as marsh gas.
(3) The term petroleum means ___
(4) Heating coal in the absence of air is called ___
(5) An example for fossil fuel is ___
Answer :
(1) → Carbon monoxide and Nitrogen
(2) → Methane
(3) → Rock and oil
(4) → Destructive distillation
(5) → Petroleum
(IV) Answer briefly
(1) What do you mean by catenation?
Answer :
The property of carbon atom to form bonds with itself resulting in a single large structure or chain is known as catenation.
(2) Mention the advantages of natural gas
Answer :
The advantages of natural gas are –
(a) it produces lot of heat as it can be easily burnt.
(b) It does not leave any residue.
(c) It burns without smoke
(d) It can be easily supplied through pipes.
(3) Expand CNG. List out its uses.
Answer :
CNG stands for – Compressed Natural Gas
Uses :
(a) It is used in vehicles.
(b) It is less expensive than petrol and diesel therefore it is used in all types of vehicles.
(c) It is used in manufacture of chemicals , glass, steel etc.
(4) Identify the gas known as syngas. Why is it called so?
Answer :
The water is the mixture of carbon monoxide and hydrogen. And it is also known as syngas.
It is also called synthesis gas because it is used to synthesize methanol and simple hydrocarbons.
(5) Anthracite is known as the highest grade coal. Give reason.
Answer :
Anthracite is known as the highest grade coal because it is the most desirable one and it has high heat content therefore it is known as the highest grade coal.
(6) Distinguish between octane number and cetane number.
Answer :
Octane number :
- Octane number is used for petrol.
- It measures the amount of octane present in petrol.
- Octane number of petrol can be increased by adding benzene or toluene.
- The fuel with the high octane number has low cetane number.
Cetane number :
- Cetane number is used for diesel.
- It measures the ignition delay of the fuel in diesel engine.
- Cetane number of diesel can be increased by adding acetone.
- The fuel with high cetance number has low octane number.
(V) Answer in detail
(1) Explain the different types of coal.
Answer :
Coal is the fossil fuel. it is the mixture of free carbon and compounds of carbon containing hydrogen, oxygen, nitrogen and sulphur. Mainly coals have four types
(a) Lignite : it is a brown colored coal of lowest grade. It has the lowest carbon content almost 25-35%. It contains high amount of water and makes up almost half of our total coal reserves. It is used for electricity generation.
(b) Sub-bituminous : when lignite becomes darker and harder time sub-bituminous coal is formed. This coal is a black and dull coa. It has higher heating value than lignite and contains 35-44% carbon. This coal is also used for electricity generation.
(c) Bituminous : bituminous coal is dark and hard. It contains 45-86% carbon. It has high heating value. It is used to generate electricity. The important used of this coal is to provide coke to iron steel industries.
(d) Anthracite : it is the highest grade coal. It has a very light weight and the highest heat content. This coal is very hard, deep black, and shiny. It contains 86-97% carbon and has a heating value slightly higher than bituminous coal. It burns longer with more heat and less dust.
(2) What is known as destructive distillation? Write about the products obtained from fractional distillation of petroleum.
Answer :
Destructive distillation : the process of heating coal in the absence of air is called destructive distillation of coal. The destructive distillation is carried out in the laboratories. In this process some by products are obtained like coke, coal tar, ammonia and coal gas.
Fractional distillation : the process of heating a mixture of liquids having different boiling points and then separating them by cooling is called fractional distillation.
Products obtained from fractional distillation are as followings :
Refinery gas, petrol, naphtha , kerosene, diesel, lubricating oil, fuel oil, crude oil, etc. are the products obtained form fractional distillation.
(3) Explain the different types of fuel gases.
Answer :
Fuel is defined as the any substance that can produce heat and energy on burning is called fuel. There are three types of fuels :
(a) Solid fuels : fuels like wood and coal are in solid state and they are called solid fuels. This type of fuel was the first one to be used by man. These fuels are easy to store and transport. The production cost is also very low.
(b) Liquid fuels : most of the liquid fuels are derived form the fossil remains of dead plants and animals. Petroleum oil, coal tar and alcohol are some of the liquid fuels. These give more energy on burning and burn without ash.
(c) Gaseous fuel : coal gas, oil gas ,producer gas and hydrogen are some of the gaseous fuels. These fuels can be easily transported through pipes and they are not produce pollution
These are the three types of fuels.
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