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Chemistry Chapters

12th Class Chapter 16 Chemistry Short Questions

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Question: 1
What is recycling of raw material?
Answer: 1
1-34
In recycling some of the used or waster material are not discard after their initial use but are processed so that they can be used again,The purpose of recycling is to converse sources such as raw material and energy.
Question: 2
What is leachate?
Answer: 2
2-34
The groundwater which seeps in the landfill and liquid from the waster itself all percolate through the refuse producing leachate,The leachater contains dissolved ,suspended and microbial contaminants.
Question: 3
What are sulphate aerosols?
Answer: 3
3-34
SO2,SO3because of their pungent odour are very irritated and uccocating through various reaction in the atmosphere they form sulphate aerosols,These aerosol cause sever respiratory troubles particularly among older people.
Question: 4
How gases in the atmosphere absorb?
Answer: 4
4-34
The gases in the atmosphere absorbs most of the cosmic rays and the major portion of the harmful electromagnetic radiation coming from the sun,The absorption of these harmful radiation protects the life on the earth.
Question: 5
What are the effects of dumping waste in sea and rivers.
Answer: 5
5-34
Water covers more than 710% of the earth and is valuable source for food and mineral,Sea and rivers have long been used for dumping waste of industries and municipal discharges such as acids,refinery wastes,pesticides water,garbage and radioactive waste etc.
Question: 6
What is lithosphere?
Answer: 6
6-34
It consists of rigid rocky crust of earth and extends to the depth of 100 km,The mantle and core are the heavy interior of the earth,making up most of the earth mass,The 99.5% mass of the lithosphere is made of 11 elements,which are oxygen,Si,Al,Fe,Ca,Na,K,Mg And Ti,H2and P.The elements in trace amount are C,Mn,S,Ba,CI,Cr,F,Zr,Ni,Sr and V,These elements mostly occur in the form off mineral.
Question: 7
Discuss Detergent as water pollutants?
Answer: 7
7-34
Detergents are excessively used in industry and household as cleaning agents,The amount of disposed detergent in waste water is increasing day by day,This waste water when discharged in rivers,sea ,greatly affects the aquatic life.
Question: 8
Define ecosystem.
Answer: 8
8-34
Ecosystem is a similar unit of biosphere which consists of community of organisms and their zone and depend on physical factor such as soil water and air.
Question: 9
Define environmental chemistry and what are the components of Environment?
Answer: 9
9-34
Environmental chemistry deals with the chemicals and other pollutants in the environment,In this way we study the sources,reaction ,transportation of the chemical and other toxic substance especially created by human activity in the environment and their adverse effect on human being.
The environment consists of the following
1.Atmosphere
2.Hydrosphere
3.Lithosphere
4.Biosphere
Question: 10
What is Biosphere?
Answer: 10
10-34
Biosphere is the region of earth capable of supporting life.It includes lower atmosphere ,the oceans,rivers,soils and solid sediments that activity interchange material with all types of living organism i,e human beings animals,and plants.
Question: 11
What is landfill?
Answer: 11
11-34
The municipal solid waste is mainly disposed off by dumping it in landfill,The landfill is large hole in the ground or even a bare piece of land when the landfill becomes full with water it is covered by soil or clay.,
Question: 12
How detergent are treat to aquatic animal?
Answer: 12
12-34
Detergents are excessively used in industry and household as cleaning agents,The amount of disposed detergent in waste water is increasing day by day,This waste water when discharged in rivers,sea ,greatly affects the aquatic life.Detergent content of waste water mobilize the bound toxic ions of heavy metals.
Question: 13
Discuss photochemical smog and give its properties?
Answer: 13
13-34
Photochemical smog consists of higher concentration of oxidants like ozone and is also termed as oxidizing smog.It is a yellowish brownish grey haze which is formed in the presence of water droplets and chemical reactions of the pollutants in the air.It has unpleasant odor because of its gaseous components.
Question: 14
What are primary and secondary pollutants in atmosphere?
Answer: 14
14-34
Primary Pollutants:The waste product given out from chimneys of industrial units and exhaust of automobiles may contain gases such as sulphur dioxide.sulphur trioxide,nitrogen oxides,carbon monoxide compound of fluorine and radioactive material .The waste products are called primary pollutants.
Secondary Pollutants:The primary pollutants in the atmosphere through various reaction product some pollutants such as sulphuric acid,nitrogen monoxide,carbonic acid,Hydrofluoric acid keatons and peroxybenzolara called secondary pollutants.
Question: 15
Name the factors which affects the quantity of water?
Answer: 15
15-34
  1. Dissolved Oxygen
  2. Biochemical Oxygen Demand
  3. Chemical Oxygen Demand
Question: 16
Why "CO' Carbon monoxide is highly poisonous gas.
Answer: 16
16-34
Carbon monoxide is highly poisonous gas and cause suffocation if inhaled.It blinds blood hemoglobin more strongly than oxygen than oxygen thus excluding oxygen from normal respiration.The Co poisoning can reserved by giving high pressure oxygen.
Question: 17
What are the conditions for the formation of smog?
Answer: 17
17-34
  1. There must be sufficient NO,hydrocarbons and volatile organic compound emitted by the vehicular traffic.
  2. Sunlight ,so that some of the chemical reaction may occur at a rapid rate.
  3. The movement of air mass must be little so that reaction are not disturbed,.
Question: 18
What are the primary pollutants?
Answer: 18
18-34
The waste product given out from chimneys of industrial units and exhaust of automobiles may contain gases such as sulphur dioxide.sulphur trioxide,nitrogen oxides,carbon monoxide compound of fluorine and radioactive material .The waste products are called primary pollutants.
Question: 19
Why ozone layer has depleting?
Answer: 19
19-34
The concentration of ozone in the stratosphere is behind depet through various chemical reaction but the it is seriously affected by chlorofluorocarbons.chlorofluorocarbons used as refrigerants in air conditioning and in aerosol spray are inert in the troposphere but slowly diffuse into stratosphere ,where they are subjected to ultraviolet radiation generating Ci free radicals which react with ozone and cause depletion.
Question: 20
What are the secondary pollutants?
Answer: 20
20-34
The primary pollutants in the atmosphere through various reaction product some pollutants such as sulphuric acid,nitrogen monoxide,carbonic acid,Hydrofluoric acid keatons and peroxybenzolara called secondary pollutants.
Question: 21
What does coagulation mean?
Answer: 21
21-34
The material which are present or suspended in the colloidal form in raw water are removed by coagulation process,The coagulation such as aluminium sulphate or alum is added to the raw water which cause the precipitated of suspended impurities.
Question: 22
Write the harmful effects of Chlorination of water?
Answer: 22
22-34
Harmful effects of chlorination of water are due to its reaction with dissolved ammonia and organic matters present in water,The hypochlorous acid reacts with dissolved ammonia to form chloramines .
Chlorination of water containing organic material aslo forms some organic compound which are toxic.
Question: 23
What is the effect of Acid rain on earth?
Answer: 23
23-34
Acidification of the soil and rocks can leach metals like aluminium ,mercury ,lead and calcium and discharges them into water bodies.These heavy metals are accumulated in the fished and are health hazards for human and birds they eat these fishes,The elevated concentration of aluminium is harmful for fished as it clogs the gills this causing suffocation,Acidification of the soil can also each nutrient thus damaging leaves and plants and growth of forest.
Question: 24
What is Acid Deposition?How does it affect the building material?
Answer: 24
24-34
The rain contains acid is called acid rain now a days it termed as acid deposition,It produce serious environmental problems.Acid rain is produced due to the presence of CO2and NOxin atmosphere convert it into carbon dioxide,.ACid rain damage building material such as steel,pain,plastics ,cement masonry work.
Question: 25
What is chemical oxygen demand?How it is measured?
Answer: 25
25-34
The organic content of water which consumes oxygen during chemical oxidation is evaluated by its chemical oxygen demand.The oxygen demand of water can be determined directly by treating it with dichromate ions, which is powerful oxidizing agent,The organic matter in water oxidized,while the remaining dichromate is determined titrimetrically.
Question: 26
What is smog?What are the content of photochemical smog?
Answer: 26
26-34
The word smog is combination of smoke and fog,Photochemical smog consists of higher concentration of oxidants like ozone and is also termed as oxidizing smog,The main reactants of photochemical smog are nitric oxide NO and unburnt hydrocarbons,Nitric acid is oxidizing to nitrogen dioxide within minutes to hours depending upon the concentration of pollutants gas.
Question: 27
What are the cause of water pollution?
Answer: 27
27-34
Surface and groundwater which are vital resources of freshwater are vulnerable to contamination,The human activities such as livestock waste,landfills agriculture,pesticides,oil leaks and spills,disposal of industrial effluents on open land ,water bodies septic tanks,and natural gas production may result in the water pollution.
Question: 28
What is effect of aeration on quality of raw water?
Answer: 28
28-34
The quality of raw water is improved by aeration.In this process air is passed through water to remove the dissolved gasses such as foul smelling,organo-sulphur compound and volatile organic compound,Some of the organic material in the raw water which could be easily oxidized with air produce in the aeration process,.
Question: 29
Detergents are threat to aquatic life.Explain.
Answer: 29
29-34
Detergents are excessively used in industries and households as cleaning agents.The amount of disposed detergents in waste water is increasing day-by day,This waster water when discharge in river or sea,greatly affects the aquatic life.
Question: 30
What is biochemical oxygen demand?
Answer: 30
30-34
It is the capacity of an organic matter in natural water to consume oxygen within a period of five days.The value of BOD is the amount of oxygen consumed as a result of biological oxidation of dissolved organic matter is a sample.The oxidation reaction is catalyzed by microorganism which are already present in a natural water.It is measured experimentally by calculating the concentration of oxygen at the beginning and at the end of 5 days period in which a sealed water sample is maintained in dark at constant temperature either at 20 degree or 25 degree.
Question: 31
How do leather tanneries pollute the water?
Answer: 31
31-34
Many leather tanning units,varying from the cottage scale to big industrial units are working in and around many big cities of Pakistan.They use large quantities of chromium salts for leather tanning,They are producing goof variety of exportable leather but only some units has facing the facilities of waste water treatment by reducing Cr into trivalent state followed by alkaline precipitation by of Cr(OH)3.These industries are the big source of chromium pollution on the environment ,Chromium is highly toxic an is known cause cancer.
Question: 32
How ozone layer in stratosphere is affected by chlorofluorocarbons?
Answer: 32
32-34
Chlorofluorocarbons used as refrigerants in air conditioning and in aerosol spray are inert in the troposphere but slowly diffuse into stratosphere ,where they are subjected to ultraviolet radiation generating Ci free radicals which react with ozone and cause depletion.
Question: 33
What do you know about reducing smog and oxidizing smog?
Answer: 33
33-34
The smog contain high content of So2it is chemically reducing in nature and is known as reducing smog,The main cause of reducing smog is combustion of coal.Photochemical smog consists of higher concentration of oxidants like ozone and is also termed as oxidizing smog,
Question: 34
Explain purification of water by use of coagulating agent.
Answer: 34
34-34
The coagulant such as aluminium sulphate or alum is added to the raw water,which cause the precipitation of suspend impurities,For example aluminium hydroxide is precipitated when alum is added to water in alkaline medium.
Many suspended particles get absorbed on the surface of gelatinous aluminium hydroxide precipitate,Ferric salts are commonly used as coagulants but they are difficult to handle.

12th Class Chemistry Chapters Short Questions