Instruction
- Total number of questions : 20
- Time allotted : 30:00 Minutes:Seconds.
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Chemical Process Technology [ Question No: 1 To 20 ] :
A paint is 45 per cent solids by volume. What dry film thickness results from applying a wet film of 100 micrometres?
Arrange the stages of paint manufacture in order.
1. let down with the rest of the binder and solvent
2. premix the pigment with part of the binder
3. tint, adjust and filter before filling
4. disperse the pigment in a mill
State whether the following is true or false.
A thermoplastic can be melted and reshaped repeatedly.
Consider the following statements about refinery hydrogen.
1. Catalytic reforming is a significant source of it.
2. Hydrotreating and hydrocracking are large consumers.
3. Most refineries have a surplus of hydrogen.
Assertion (A): A fat is solid at room temperature while an oil is liquid.
Reason (R): Saturated and longer chains pack more readily into a crystal than unsaturated ones.
Sterilisation of the medium before a fermentation is necessary because
State whether the following is true or false.
Sugar juice is concentrated in a single evaporator body.
Assertion (A): Imbibition water is added between the mills of a cane tandem.
Reason (R): Diluting the residual juice in the bagasse lets the following mill extract more of the sugar.
Arrange the sections of a Fourdrinier paper machine in order.
1. press section removing more water mechanically
2. headbox delivering the stock
3. dryer section evaporating the rest
4. wire section where the sheet forms and drains
Assertion (A): Bleaching demand is estimated from the kappa number of the unbleached pulp.
Reason (R): The number measures the residual lignin, which is what the bleaching chemicals attack.
Mechanical pulping gives a much higher yield than chemical pulping because it
Match each wood component with its role or fate in pulping.
List I
A. Cellulose
B. Lignin
C. Hemicellulose
D. Extractives
List II
1. partly retained, aiding fibre bonding
2. the fibre that becomes the paper
3. resins and fats removed as tall oil or pitch
4. the binder that must be dissolved away
Soda ash is added to a glass batch in order to
State whether the following is true or false.
Granulation is preferred to simple blending of powders for a multi-nutrient fertiliser.
Diammonium phosphate is made by reacting
Chlorine is normally shipped and stored
Three of the following are raw materials for the Solvay process. Which is the odd one out?
All of the following are products or co-products of a chlor alkali plant EXCEPT
At the anode of a chlor alkali cell the reaction produces
Assertion (A): A chlor alkali plant cannot adjust its caustic to chlorine ratio to suit the market.
Reason (R): Both are produced by the same electrolysis in a ratio set by the stoichiometry.
Total number of questions : 20
Number of answered questions : 0
Number of unanswered questions : 20
Chemical Process Technology [ Question No: 1 To 20 ] :
A paint is 45 per cent solids by volume. What dry film thickness results from applying a wet film of 100 micrometres?
Your Answer : (Not Answered)
Correct Answer : C
The solvent leaves, so the dry thickness is the wet thickness times the volume solids. This is the calculation a specifier uses to decide how many coats a protective system needs. Wet film gauges are used to check it as applied.
Arrange the stages of paint manufacture in order.
1. let down with the rest of the binder and solvent
2. premix the pigment with part of the binder
3. tint, adjust and filter before filling
4. disperse the pigment in a mill
Your Answer : (Not Answered)
Correct Answer : B
Dispersion is the heart of the process and works best on a thick paste, which is why the let down follows rather than precedes it. Adjustment to colour and viscosity is always the last step. Filtration removes any remaining coarse material.
State whether the following is true or false.
A thermoplastic can be melted and reshaped repeatedly.
Your Answer : (Not Answered)
Correct Answer : A
Its chains are held together only by physical forces, which soften on heating. A thermoset has covalent crosslinks that decompose rather than soften, so it cannot be remoulded. Recycling therefore works only for the thermoplastics.
Consider the following statements about refinery hydrogen.
1. Catalytic reforming is a significant source of it.
2. Hydrotreating and hydrocracking are large consumers.
3. Most refineries have a surplus of hydrogen.
Your Answer : (Not Answered)
Correct Answer : B
The first two are correct. The third is generally false today, since tightening fuel specifications have made most refineries net importers or builders of dedicated steam reforming units. Sulphur limits drove the change over two decades.
Assertion (A): A fat is solid at room temperature while an oil is liquid.
Reason (R): Saturated and longer chains pack more readily into a crystal than unsaturated ones.
Your Answer : (Not Answered)
Correct Answer : C
Both are true and the reason gives the cause: a cis double bond puts a kink in the chain that prevents close packing, which is why unsaturated oils stay liquid to much lower temperatures. Trans isomers pack almost as well as saturated chains.
Sterilisation of the medium before a fermentation is necessary because
Your Answer : (Not Answered)
Correct Answer : D
Correct answer: a contaminant would outgrow the culture
A fermentation medium is a rich growth substrate at a comfortable temperature, so any organism entering it will grow - and a contaminant with a shorter generation time will overtake the production strain and consume the substrate for nothing. The whole vessel is then lost. Sterilising the medium, the air and the vessel is therefore a precondition rather than a precaution.
State whether the following is true or false.
Sugar juice is concentrated in a single evaporator body.
Your Answer : (Not Answered)
Correct Answer : B
Multiple effect evaporation is used, with the vapour from one body heating the next, because a single body would consume several times as much steam. Four or five effects are usual in a cane factory. Vapour bleeding supplies heat elsewhere in the plant.
Assertion (A): Imbibition water is added between the mills of a cane tandem.
Reason (R): Diluting the residual juice in the bagasse lets the following mill extract more of the sugar.
Your Answer : (Not Answered)
Correct Answer : B
Both are true and the reason gives the purpose: the water flows counter-current to the cane, so the cleanest water meets the most exhausted bagasse and the extraction approaches its limit. The last mill sees the cleanest water of all.
Arrange the sections of a Fourdrinier paper machine in order.
1. press section removing more water mechanically
2. headbox delivering the stock
3. dryer section evaporating the rest
4. wire section where the sheet forms and drains
Your Answer : (Not Answered)
Correct Answer : A
Correct answer: 2 - 4 - 1 - 3
The stock arrives at about one per cent consistency and water is removed in order of increasing cost. The headbox spreads it evenly across the width, the wire drains most of the water by gravity and suction, the presses squeeze out more mechanically, and only the last few per cent is evaporated in the dryers. Evaporation is by far the most expensive route, which is why so much effort goes into the sections before it.
Assertion (A): Bleaching demand is estimated from the kappa number of the unbleached pulp.
Reason (R): The number measures the residual lignin, which is what the bleaching chemicals attack.
Your Answer : (Not Answered)
Correct Answer : D
Both are true and the reason gives the connection: cooking to a lower kappa costs yield, so the mill trades cooking against bleaching to reach the brightness it needs at least cost. Cooking too hard damages the fibres as well.
Mechanical pulping gives a much higher yield than chemical pulping because it
Your Answer : (Not Answered)
Correct Answer : C
Yields above ninety per cent are possible because nothing is dissolved away, but the retained lignin makes the paper weak and prone to yellowing. Newsprint is the classic product. Chemical pulping sacrifices half the wood for strength.
Match each wood component with its role or fate in pulping.
List I
A. Cellulose
B. Lignin
C. Hemicellulose
D. Extractives
List II
1. partly retained, aiding fibre bonding
2. the fibre that becomes the paper
3. resins and fats removed as tall oil or pitch
4. the binder that must be dissolved away
Your Answer : (Not Answered)
Correct Answer : B
Knowing what each fraction does explains why yields differ so widely between mechanical and chemical pulping. Only the cellulose is wanted in full, and the others are removed to varying degrees. Yield follows directly from how much is dissolved.
Soda ash is added to a glass batch in order to
Your Answer : (Not Answered)
Correct Answer : C
Correct answer: lower the melting temperature usefully
Pure silica melts near 1,700 degrees, which is impractical for volume production. Sodium oxide from the soda ash disrupts the silica network and brings the melting temperature down by several hundred degrees. What it does not do is improve the glass - it makes it soluble, which is why lime must be added alongside it.
State whether the following is true or false.
Granulation is preferred to simple blending of powders for a multi-nutrient fertiliser.
Your Answer : (Not Answered)
Correct Answer : C
Correct answer: True
A blend of powders segregates during handling, since the components differ in particle size and density, so the analysis at the field is not the analysis on the bag. Granulating the nutrients together puts all of them into every granule, which cannot separate; the granules also flow better, dust less and resist caking. The cost is the granulation plant, which blending avoids.
Diammonium phosphate is made by reacting
Your Answer : (Not Answered)
Correct Answer : C
The reaction is strongly exothermic and the product supplies both nitrogen and phosphate, typically at eighteen and forty-six per cent. Monoammonium phosphate is made the same way with less ammonia. Both are widely traded as compound fertilisers.
Chlorine is normally shipped and stored
Your Answer : (Not Answered)
Correct Answer : C
Correct answer: as a liquid under pressure
Chlorine liquefies at moderate pressure at ambient temperature, and shipping it as a liquid reduces the volume by a factor of several hundred. It is carried in pressure vessels, road tankers and rail cars, and because a release would flash to a dense toxic gas, the storage and transport of chlorine are among the most heavily regulated in the chemical industry.
Three of the following are raw materials for the Solvay process. Which is the odd one out?
Your Answer : (Not Answered)
Correct Answer : A
Correct answer: sulphur dioxide gas
The Solvay process uses brine, limestone and ammonia. The limestone is calcined to give carbon dioxide and lime, the carbon dioxide and ammonia react with the brine to precipitate sodium bicarbonate, and the lime recovers the ammonia from the ammonium chloride so that it circulates rather than being consumed. Sulphur dioxide has no part in it.
All of the following are products or co-products of a chlor alkali plant EXCEPT
Your Answer : (Not Answered)
Correct Answer : D
Correct answer: sulphuric acid
A chlor alkali plant makes chlorine, caustic soda and hydrogen - the three products of electrolysing brine. Sulphuric acid is not among them; it may well be *bought in* for drying the chlorine, but it is a raw material to the plant rather than a co-product of it.
At the anode of a chlor alkali cell the reaction produces
Your Answer : (Not Answered)
Correct Answer : A
Chloride is oxidised to chlorine, while hydrogen and hydroxide appear at the cathode. A little oxygen is also formed at the anode as an unwanted side reaction that lowers the current efficiency. Anode coatings are chosen to suppress it.
Assertion (A): A chlor alkali plant cannot adjust its caustic to chlorine ratio to suit the market.
Reason (R): Both are produced by the same electrolysis in a ratio set by the stoichiometry.
Your Answer : (Not Answered)
Correct Answer : C
Correct answer: Both A and R are true, and R is the correct explanation of A
Both are true and the reason is the cause. The electrolysis produces one mole of chlorine for every two of caustic soda, and no operating change alters that ratio - it is fixed by the chemistry. The industry therefore lives with a structural problem: demand for the two products moves independently, so one is often in surplus while the other is short, and the plant can only respond by changing its total rate.
Marks
Total number of questions : 20
Number of answered questions : 0
Number of unanswered questions : 20