12th Class Chemistry Chapter 15 Short Questions with Answers Solved

Question: 1

What reaction were taking place in the first 24 hour during setting of cement?

Answer: 1

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A short time after the cement is mixed with eater tricalcium aluminate absorbs water and forms a colloidal gel of the composition,

The gel starts crystallizing slowly,reacts with gypsum to form the crystal of calcium sulphoaluminate.

Question: 2

What is the role of potassium in growth of plants?

Answer: 2

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Potassium is required for the formation of starch sugar and the fibrous material of the planet.They increase resistance to disease and make the plant strong by helping in healthy root development.Potassium fertilizers are especially used for tobacco,coffee and corn.

Question: 3

Give an idea about Clinker.

Answer: 3

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The resulting product obtained from the kiln is known as cement clinker,This has the appearance of greenish black or grey coloured balls varying in size from small nuts to peas.

Question: 4

What is phosphatic fertilizer?

Answer: 4

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The fertilizer provide phosphorus to the planet or soil ,Various phosphate fertilizer have different compositions,The most important water soluble fertilizer are super phosphate and triple phosphate .

Question: 5

Define cement.Give its essential components.

Answer: 5

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Cement is the material obtained by burning an intimate mixture of calcarious and argillaceous material at sufficiently high temperature to produce clinkers.These clinker are the ground to a fine powder.'

Essential components of cements:

1.Calcarious material as source of CaO.

2.Argillaceous material they provide acidic components such as aluminates and silicates.

3.Gypsum

Question: 6

Just write five stage in the manufacturing of Portland Cement?

Answer: 6

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Crushing and Grinding
Mixing of the raw material
Heating the slury in a Rotary Kiln
Clinker formation
Grinding the clinker with gypsum.

Question: 7

What is difference between clinker and cement?

Answer: 7

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Clinker : The resulting product obtained from the kiln is known as cement clinker,This has the appearance of greenish black or grey coloured balls varying in size from small nuts to paes.

Cement: Cement is the material obtained by burning an intimate mixture of calcareous and argillaceous material at sufficiently high temperature to produce clinker.

Question: 8

What do you mean by calcareous material and argillaceous material; used for the manufacturing of cement?

Answer: 8

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Calcarious material:(Limestone,marble ,chalks,marine shell)as source of CaO.

Argillaceous material:Argillaceous material (clay,slate,shale,blast,furnace)they provide acidic components such as aluminates and silicates.

Question: 9

Why nitrogen is important for plants?

Answer: 9

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Nitrogen is required during the early stage of plant growth for the development of stems and leaves,It is the main constituents of protein ,impar green colour to the leaves an enhance the yield and quality of the plants.

Question: 10

Explain the importance of potassium fertilizer.

Answer: 10

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Potassium fertilizer provide potassium to the plant or soil.Potassium is required for the formation of starch,sugar an the fibrous material of the planet,That increase resistance to disease and make the plant more strong by helping in healthy root development,They also help in ripening of seeds,fruits and cereals.

Question: 11

What is the function of phosphatic fertilizer in plants?

Answer: 11

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Phosphorus is required to stimulate early growth to accelerate the seed and fruit formation during the later stage of growth,It also increase resistance to disease,The various phosphatic fertilizer have different composition due to which they have different solubilities.

Question: 12

Give different zones in the rotary kiln and their temperature.

Answer: 12

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1.Dying or pre heating zone..

2.Decomposition zone.

3.Burning Zone

4.Cooling Zone

Question: 13

What do you know about screening operation for pule and paper industry.

Answer: 13

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In most pulp and paper process some types of screening operation id required to remove the over sized troublesome and unwanted particle,Magnetic separator removed iron pieces like nail and bolts .

Question: 14

How digestion process is carried out in paper industry?

Answer: 14

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From wet digestion,the material is sent to digester ,The digester is usually 10 meters in length and 2 meters in diameter,It is made of steel and wrought iron,This is the main unit of process,The digestion process can be either batch or continuous.As the raw material enter into digester steam is introduced at the bottom and a liquor containing sodium sulphate is injected simultaneously to cover the raw material.

Question: 15

Define paper ,Give important raw material for the manufacture of paper?

Answer: 15

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It is defined in term of its method of production,that is a sheet material made up of a network of natural cellulosic fibres which have been deposited from an aqueous suspension The product obtained is a network of interwinning fibres.

The main raw material used in the production of pulp and paper in Pakistan is of two types that is non woody and raw material.

Question: 16

Write down four major component of paper machine?

Answer: 16

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Flow spreader
Head box
press section
dryer section.

Question: 17

How lignin is removed from paper?

Answer: 17

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The pulb is washed with required amount of water soluble lignin and coloured compound,Lignin is an aromatic polymer and cause paper to become brittle,It is then thickened finally stored in high density storage tower.

Question: 18

What are fertilizer and why they are required?

Answer: 18

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Fertilizers are the substance added to the soil to make up the deficient of essectial elements like nitrogen,phosphorus and potassium require for the proper growth of plants.Fertilizer enhance the natural fertility of the soil or replenish the chemical elements take up from the soil by the previous crops,.

Question: 19

What are the common bleaching agent used in paper industry in Pakistan?

Answer: 19

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IN Pakistan ,bleaching is done with chlorine dioxide or sodium hypochlorite and hydrogen peroxide.

Question: 20

Define lignin?Write its effect on paper?

Answer: 20

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Lignin is an aromatic polymer and causes paper to become brittle.

Wet sheet is dried in drying section of machine with the help of rotary drum,Water is separated from fiber either by gravity by section or by pressing or by heating,.

Question: 21

Define the term paper.

Answer: 21

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It is defined in term of its method of production,that is a sheet material made up of a network of natural cellulosic fibres which have been deposited from an aqueous suspension The product obtained is a network of interwinning fibres.

Question: 22

How clinker is converted into cement?

Answer: 22

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The cement clinker are air cooled and groud with required of gypsum into fine powder.

Question: 23

Why wet cleaning is done in paper manufacture?

Answer: 23

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Wet cleaning removes the remaining dust particles,and the soluble materials get dissolved in water.

Question: 24

What are fertilizer and what are they needed?

Answer: 24

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Fertilizers are the substance added to the soil to make up the deficient of essectial elements like nitrogen,phosphorus and potassium require for the proper growth of plants.Fertilizer enhance the natural fertility of the soil or replenish the chemical elements take up from the soil by the previous crops.

Question: 25

What is meant by Dry cleaning in Paper manufacturing?

Answer: 25

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Wheat straw is collected from the storage and is then set for dry cleaning ,For this purpose air is blown into the raw material,which removes unwanted particles.

Question: 26

Write a short note on diammonium phosphate?

Answer: 26

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This compound of fairly high purity is prepared by continuous process that consists of reacting anhydrous ammonia gas and pure phosphoric acid at 60-70 degree and pH 5.8-6.0.

Question: 27

Enlist the step involved in the manufacturing of urea?

Answer: 27

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Following are the steps included in manufacturing of urea.

Preparation of hydrogen
Preparation of ammonia
Preparation of Ammonium carbamate
Prilling
Concentration of Urea

Question: 28

Brief about prilling of urea?

Answer: 28

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The molten urea is sprayed at the prilling tower by means of prilling bucket where it is cooled by the air rising upward,Molten droplets solidify into the form of prills,Urea prills thuis produced are either sent to the bagging section or to the bulk storage.

Question: 29

Distinguish between fertilizer and non fertilizer compound?

Answer: 29

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Compound of elements namely nitrogen,phosphorus and potassium are considered to be the most important nutrients essential for plant growth.The element like sulphur ,magnesium and calcium are considered for secondary importance,These compounds are called fertilizer compound.

While those compounds which are not require as nutrients for a fertilizer is called no fertilizer compounds.

Question: 30

Ammonium nitrate is useful fertilizer for many crops expect paddy rice,Why?

Answer: 30

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Ammonium nitrate can not be used as fertilizer for paddy rice because the microbial bacteria is flooded fields decomposes it ti nitrogen gas.

Question: 31

Write the important qualities of a good fertilizer?

Answer: 31

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The nutrient elements present in it must be readily available to the plant.It must be fairly soluble in water so that it thorough mixes with the soil.It should be cheap.It should not be injurious to plant.It must be stable so that it is available for a longer time to the growing plant.

Question: 32

Give percentage of nitrogen in urea ,ammonium nitrate,hydrogen phpsphate.

Answer: 32

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Percentage on nitrogen in Urea is 46%

Percentage of nitrogen in ammonium nitrate =33-33.5%

Percentage if nitrogen in Diammonium hydrogen phosphate=16%

Question: 33

Distinguish micronutrients and macronutrients for plants?

Answer: 33

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Micronutrients : The nutrient which are require in a very small amount for the growth of plants are called micronutrients,These include Boron,Copper ,iron,Manganese,Zinc.

Macronutrients :The nutrients which are required in a large amount for the growth of plants are called macro-nutrients,These include Nitrogen ,Phosphorus ,Potassium,Calcium and Oxygen.

Question: 34

Give the important properties of Fertilizer?

Answer: 34

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