Chemistry In Everyday Life Online Test 8th Science Lesson 20 Questions in English

Explanation

Chemistry is in the air we breathe, the food we eat and everything we use in our daily life. We are nothing without chemistry even our body is made of elements like nitrogen, phosphorous, hydrogen, oxygen, calcium, potassium, sulphur, magnesium etc.

Explanation

Our whole life is dependent on various chemical compounds. Among them, hydrocarbons are the most important one. We can say that the whole civilization is driven by hydrocarbons because they make up the fossil fuels petroleum and natural gas.

Explanation

Hydrocarbons occur naturally and they are found in fossil fuels like crude oil, natural gas and coal. Hydrocarbons are the organic compounds consisting of hydrogen and carbon atoms. They are combustible and produce large amount of heat energy along with carbon dioxide and water vapour, on burning.

Explanation

Most of the hydrocarbons are insoluble in water.

Explanation

Most hydrocarbons react with oxygen to produce carbon dioxide and water.

Explanation

In hydrocarbons carbon and hydrogen atoms are linked together through different chemical bonds. Depending on the bond between these atoms there are number of hydrocarbons. The four general classes of hydrocarbons are: alkanes, alkenes, alkynes and arenes.

Explanation

Some of the common hydrocarbons are methane, ethane, butane, pentane and propane

Explanation

Methane is the simplest hydrocarbon in which four hydrogen atoms are linked with one carbon atom.

Explanation

Methane – CH₄; Ethane – C₂H₆; Propane – C₃H₈; Butane – C₄H₁₀; Pentane – C₅H₁₂.

Explanation

Methane is the simplest hydrocarbon in which four hydrogen atoms are linked with one carbon atom. It is a colourless, odourless and inflammable gas. It is an eco-friendly fuel because it does not produce any harmful products. It is used as a fuel in electricity generation.

Explanation

Methane is also known as marsh gas as it is present in marshes. Dead and decaying plants and animals release methane gas. It is a renewable source of energy.

Explanation

Sewage sludge can also be decomposed by microorganisms to produce methane gas along with impurities like carbon dioxide and hydrogen sulphide. After removing these impurities, methane gas can be used as an efficient fuel.

Explanation

Propane is liquefied through pressurisation and commonly used as LPG (Liquefied Petroleum Gas) along with butane.

Explanation

Propane is heavier than air. Propane is used as fuel in heating, cooking, and vehicles.

Explanation

Propane is used in LPG cylinders. Since it is an odourless gas, any leakage cannot be detected. Hence, a chemical by name Mercaptan is mixed with LPG to help in detection of any leakage of LPG.

Explanation

Butane is used as a fuel gas and propellant in aerosol sprays such as deodorants.

Explanation

Butane is a gas at room temperature and atmospheric pressure. They are highly flammable, colorless gases that quickly vaporize at room temperature.

Explanation

Pentanes are liquids with low boiling point. They are used as fuels and solvents in the laboratory. They are also used to produce polystyrene.

Explanation

Natural gas is a naturally occurring hydrocarbon gas mixture consisting primarily of methane along with other higher alkanes and a small percentage of carbon dioxide, nitrogen and hydrogen sulphide (H₂S).

Explanation

If the natural gas contains lower hydrocarbons like methane and ethane, it is called dry gas.

Explanation

Natural gas is always found above the oil in the oil wells. This gas is trapped inside the small spaces in underground rocks called reservoirs.

Explanation

Conventional natural gas can be extracted through drilling wells. Natural gas can also be found in reservoirs with oil and is extracted along with oil. This is called associated gas.

Explanation

Natural gas is a fossil fuel used as a source of energy for heating, cooking and electricity generation. Natural gas occurs in Tripura, Rajasthan, Maharashtra, Andhra Pradesh and Tamil Nadu.

Explanation

The natural gas occurs in Andhra Pradesh (Krishna, Godavari Basins) and Tamil Nadu (Kaveri Delta).

Explanation

Natural gas is also formed by the decomposition of organic matter in marshy areas and waste sewages. The natural gas formed by this way contains mainly methane.

Explanation

When heated natural gas decomposes and forms hydrogen and carbon. Hydrogen thus formed is used in the manufacture of fertilizers.

Explanation

When the natural gas is compressed at high pressure, it is called Compressed Natural Gas (CNG). Nowadays it is used as fuel in automobiles. The primary hydrocarbon present in CNG is methane (88.5%).

Explanation

Natural gas burns without smoke and so causes no pollution and can be easily supplied through pipes.

Explanation

Natural gas is liquefied for shipping in large tankers. This is called Liquefied Nitrogen Gas (LNG). CNG is stored at high pressure whereas LNG is stored in ultra-cold liquid form.

Explanation

CNG is less expensive than petrol and diesel.

Explanation

Apart from natural gas, there are some other gases used as fuel. Producer gas, coal gas, bio gas and water gas are some of them.

Explanation

Water gas is a gaseous mixture of carbon monoxide and hydrogen. It is made by passing steam over incandescent coke at a temperature of 1000°C.

C_(g) + H₂ O_(g) à CO_(g) + H_{2 (g)}

Explanation

Producer gas is a gaseous mixture of carbon monoxide and nitrogen. It is produced by passing air mixed with steam, over red-hot coke at a temperature of 1100 ˚C.

Explanation

Producer gas is known by different names in different countries. It is referred as Wood gas in USA and as Suction gas in UK.

Explanation

Heating coal in the absence of air is called destructive distillation. It is used in heating open hearth furnace in the manufacture of steel.

Explanation

Producer gas is used as an industrial fuel for iron and steel manufacturing.

Explanation

Bio-gas is a mixture of methane and carbon dioxide. It is produced by the decomposition of plant and animal waste which form the organic matter. The breaking down of organic matter in anaerobic condition (i.e., in the absence of oxygen) leads to the formation of biogas. It is an example for renewable source of energy.

Explanation

Water gas is also called as syngas or synthesis gas as it is used to synthesize methanol and simple hydrocarbons. It is used as an industrial fuel also.

Explanation

Coal is one of the fossil fuels. It is a mixture of free carbon and compounds of carbon containing hydrogen, oxygen, nitrogen and sulphur.

Explanation

Three hundred million years ago, some plants grew into giant ferns and mosses. These plants got buried into the bottom of the soil. They slowly started to decompose and formed a dense, sponge like material called peat. Over time peat was compressed due to high temperature and pressure and coal was formed.

Explanation

As coal contains mainly carbon, the slow process of conversion of dead vegetation into coal is called carbonization.

Explanation

Coal is extracted from the coal beds found below the surface of the earth. Coal found inside the earth is broken into pieces by explosives and brought above. Depending on the depth of the coal bed, coal is extracted in two ways. 1. Surface mining and 2. Underground mining.

Explanation

Coal reserves can be found in about 70 countries worldwide. The largest coal reserves are available in United State, Russian, China, Australia and India. The US is the international leader in coal reserves, with nearly 30% of the world’s supply.

Explanation

Coal mining was started in India in 1774.

Explanation

India now ranks third among the coal producing countries in the world. USA and China have two third of the world’s coal reserve.

Explanation

Coal is classified into four main categories based on the amounts of carbon it contains and the heat energy it can produce. They are lignite, sub bituminous, bituminous and anthracite.

Explanation

Among these four types anthracite is the most desirable one due to its high heat content.

Explanation

When lignite becomes darker and harder over time sub-bituminous coal is formed. Sub bituminous coal is a black and dull coal.

Explanation

Lignite is a brown coloured coal of lowest grade. It has least content of carbon.

Explanation

Anthracite is the highest-grade coal. It is hard and dark black in colour. It has a very light weight and the highest heat content.

Explanation

Sub Bituminous has higher heating value than lignite and contains 35-44% carbon. It is used primarily as fuel for electricity power generation.

Bituminous contains 45-86% carbon. It has high heating value. It is used to generate electricity. With more chemical and physical changes, sub-bituminous coal is developed into bituminous coal. Bituminous coal is dark and hard.

Explanation

Bituminous by-product can be converted into different chemicals which are used to make paint, nylon, and many other items.

Explanation

Anthracite 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.

Explanation

Coal is used to make derivatives of silicon which are used to make lubricants, water repellents, resins, cosmetics, hair shampoos, and toothpaste.

Explanation

Coal when heated in the absence of air does not burn but produces many by-products. This process of heating coal in the absence of air is called destructive distillation of coal. Thousands of different products have coal or coal by-products as their components. Some of them are soap, aspirins, solvents, dyes, plastics, and fibres, such as rayon and nylon

Explanation

The main by-products obtained during destructive distillation are coke, coal tar, ammonia and coal gas.

Explanation

Explanation

Coke contains 98% carbon. It is porous, black and the purest form of coal.

Explanation

Coal is largely used as a reducing agent in the extraction of metals from their ores.

Explanation

Coal tar is a mixture of different carbon compounds. It is a thick, black liquid with unpleasant smell.

Explanation

Another product obtained from coal tar is naphthalene balls which are used to repel moth and other insects.

Explanation

Coal gas also known as town gas. The gases present in coal gas are combustible and hence, it is an excellent fuel. It has high calorific value.

Explanation

Coal gas is mainly a mixture of gases like hydrogen, methane and carbon monoxide.

Explanation

The other by product obtained from coal is ammonia. It is used for making fertilizers such as ammonium sulphate, ammonium superphosphate etc.

Explanation

It is also known as Black Diamond owing to its precious nature. On destructive distillation, 1000 kg of coal gives 700 kg of coke, 100 litres of ammonia, 50 litres of coal tar and 400 m3 of coal gas.

Explanation

Petroleum is a fossil fuel formed from the remains of ancient marine organisms through death and decay. Petroleum is a complex mixture of hydrocarbons that occur in Earth in liquid, gaseous, or solid form.

Explanation

The first oil well in the world was drilled in Pennsylvania, USA in 1859.

Explanation

The term petroleum commonly denotes the liquid form, crude oil. But technically petroleum also includes natural gas and bitumen, a solid form. The natural gas and the crude oil constitute the primary fossil fuels.

Explanation

In India, petroleum is found in Assam, Gujarat, Maharashtra (Mumbai), Andhra Pradesh (Godavari and Krishna basin) and Tamil Nadu (Kaveri Basins). By drilling through the earth, the crude oil is pumped out from the well as a black liquid.

Explanation

The second oil well in world was drilled in Makum, Assam, India in 1867.

Explanation

The crude petroleum obtained from the well is a dark coloured viscous liquid which contains many impurities such as water, solid particles and gases like methane and ethane. To make it useful for different purposes, it must be separated into various components.

Explanation

The process of separating petroleum into useful by-products and removal of undesirable impurities is called refining. The crude oil obtained from the oil wells will have salt water mixed with it. As the first step the water is removed from the crude oil.

Explanation

The process of separation of various constituents or fractions of petroleum is done by fractional distillation in fractionating columns. The process of heating a mixture of liquids having different boiling points and then separating them by cooling is called fractional distillation

Explanation

The crude oil will have harmful sulphur compounds as impurities. By fractional distillation these impurities are removed. Petroleum is a mixture of various constituents such as petroleum gas, petrol, diesel, kerosene, lubricating oil, paraffin wax, etc.

Explanation

Many useful substances are obtained from petroleum and natural gas. These are termed ‘petrochemicals. These are used in the manufacture of detergents, fibres, and other man-made plastics like polythene. Hydrogen gas obtained from natural gas, is used in the production of fertilizers.

Explanation

Due to its great commercial importance, petroleum is also called ‘black gold’.

Explanation

Petrol is used as a solvent for dry cleaning.

Explanation

Any substance that can produce heat and energy on burning is called fuel. We use this heat for various purposes such as cooking, heating and many industrial and manufacturing purposes. Some of the fuels that we use in our daily life are wood, coal, petrol, diesel and natural gas.

Explanation

Fuels are classified into different types according to their physical state. They are classified into solid, liquid and gaseous fuels.

Explanation

Bitumen or asphalt is mainly used to surface roads.

Explanation

Fuels like wood and coal are in solid state and they are called solid fuels. Th is type of fuel was the first one to be used by man. Th ese fuels are easy to store and transport. Th e production cost is also very low.

Explanation

Any fuel contains carbon as its main constituent. During the combustion of fuel carbon combines with oxygen and liberates large amount of heat. It is expected that a fuel liberates maximum amount of heat in the short time.

Explanation

Calorific Value is the quantity of heat produced by the complete combustion of fuel at constant pressure and normal conditions. It is measured in terms of 125kg^-1.

Explanation

Specific energy is the amount of energy produced by unit mass of a fuel. It is defined as the energy per unit mass. It is used to measure the stored energy in certain substances.

Explanation

The unit of Specific energy is Jkg^-1.

Explanation

Cetane Number measures the ignition delay of the fuel in diesel engine. When cetane number is higher the ignition delay is shorter. The fuel with high cetane number is called as the ideal fuel.

Explanation

The fuel with high octane number has low cetane number.

Explanation

Bio diesel is a fuel obtained from vegetable oils such as soya bean oil, jatropha oil, corn oil, sunflower oil, cotton seed oil, rice-bran oil and rubber seed oil.

Explanation

Wind energy is obtained with the help of wind mills. When wind blows, they rotate the blades of the wind mills and current is produced in the dynamo. Wind mills are mostly located at Kayathar, Aralvaimozhi, Palladam and Kudimangalam in Tamil Nadu.

Explanation

Gobar gas is obtained by the fermentation of cow dung in the absence of air (anaerobic conditions). It mainly contains methane and a little ethane. It is widely used in rural areas for cooking and operating engines.

Explanation

Hydrogen could be the best alternative fuel in the future. It is a clean fuel as it gives out only water while burning. Moreover, it has the highest energy content. It does not pollute air.

Explanation

Sun is the first and foremost energy source that makes life possible on our earth. Solar energy is the only viable fuel source of non-depleting nature for, sun provides a free and renewable source of energy.

Explanation

It is used in solar water heater.

Explanation

The fractional distillation of coal tar gives many chemical substances like benzene, toluene, phenol and aniline. They are used in the preparation of dyes, explosives, paints, synthetics fibers, drugs, and pesticides.

Explanation

Cetane number of diesels can be increased by adding acetone.

Explanation

Calorific value is measured in terms of 125kg-1. The below table give calorific value of different value.