Instruction
- Total number of questions : 20
- Time allotted : 30:00 Minutes:Seconds.
- Each question carry 1 mark, no negative marks.
- DO NOT refresh the page.
- All the best
Engineering Chemistry [ Question No: 1 To 20 ] :
A nanomaterial gas sensor responds sensitively because adsorption of the gas changes the material's
As a particle's diameter falls, its surface to volume ratio
Reducing a process's solvent use from 40 kg to 10 kg per kg of product, with other waste of 5 kg, changes the E-factor from
Sonochemical activation promotes a reaction through
A renewable feedstock is preferred to a petrochemical one because it is
The retarding action of gypsum works by depositing on the tricalcium aluminate a temporary layer of
Assertion: the symmetric stretch of carbon dioxide is infrared inactive. Reason: the two bond dipoles cancel throughout the motion.
A proton spectrum shows a triplet and a quartet with integrated areas in the ratio 3 to 2. The fragment present is
A binary melt at 40 per cent B separates into a solid of 10 per cent B and a liquid of 60 per cent B. The fraction that is liquid is
Assertion: a high viscosity index is desirable in an engine oil. Reason: the oil must be thin enough to circulate when cold and thick enough to carry load when hot.
A soluble oil cutting fluid is required to emulsify readily with water in order to
High temperature carbonisation of coal, at about 1000 degrees, is carried out to make
A monomer of functionality two polymerises to give
Poly(vinyl chloride) requires a heat stabiliser during processing because it tends to
Poly(ethylene terephthalate) is made from ethylene glycol and
Galvanising is the coating of steel with
A cathodic inhibitor for a neutral aerated water may act by
Soil corrosion of a buried pipeline is aggravated by soil that is
The limiting equivalent conductance of a weak acid cannot be found by extrapolation because its equivalent conductance
A pH meter must be calibrated with standard buffers before use because the electrode's
Total number of questions : 20
Number of answered questions : 0
Number of unanswered questions : 20
Engineering Chemistry [ Question No: 1 To 20 ] :
A nanomaterial gas sensor responds sensitively because adsorption of the gas changes the material's
Your Answer : (Not Answered)
Correct Answer : D
Correct answer: electrical conductance measurably
A gas adsorbing on a nanostructured semiconductor donates or withdraws electrons, changing the carrier concentration in a body so thin that the surface effect dominates the whole conductance. The response is large, fast and reversible, which is what makes tin oxide and zinc oxide nanostructures useful as sensors.
As a particle's diameter falls, its surface to volume ratio
Your Answer : (Not Answered)
Correct Answer : C
Correct answer: rises in inverse proportion to the diameter
For a sphere, \[ \frac{S}{V} = \frac{4\pi r^2}{\frac{4}{3}\pi r^3} = \frac{3}{r} = \frac{6}{d}. \] Area falls as the square of the size and volume as the cube, so their ratio goes as the inverse of the first power. This single relation underlies nanoscale catalysis, the tendency to agglomerate, and the depression of the melting point.
Reducing a process's solvent use from 40 kg to 10 kg per kg of product, with other waste of 5 kg, changes the E-factor from
Your Answer : (Not Answered)
Correct Answer : C
Correct answer: 45 to 15
The E-factor is the total waste per kilogram of product, so it is the solvent plus the other waste: \[ 40 + 5 = 45 \quad\text{before}, \qquad 10 + 5 = 15 \quad\text{after}. \] The solvent dominates both figures, which is the general case and the reason solvent reduction is the first thing examined when an E-factor is too high.
Sonochemical activation promotes a reaction through
Your Answer : (Not Answered)
Correct Answer : A
Bubbles form and collapse violently, and the conditions inside them for a fraction of a microsecond drive chemistry the bulk temperature would not. It is particularly useful for heterogeneous reactions with a solid reagent.
A renewable feedstock is preferred to a petrochemical one because it is
Your Answer : (Not Answered)
Correct Answer : B
Correct answer: replenished on a human timescale
A renewable feedstock is one that regrows within a period comparable with its use, so it is not depleted by being consumed. Nothing else follows automatically: a renewable feedstock is not necessarily cheaper, purer, or of the same composition as its petrochemical counterpart, and its cultivation carries its own impacts.
The retarding action of gypsum works by depositing on the tricalcium aluminate a temporary layer of
Your Answer : (Not Answered)
Correct Answer : B
The sulphate reacts at the aluminate surface and the coating slows further access of water for long enough to place the concrete. The same compound formed later, from sulphate entering hardened concrete, is expansive and destructive.
Assertion: the symmetric stretch of carbon dioxide is infrared inactive. Reason: the two bond dipoles cancel throughout the motion.
Your Answer : (Not Answered)
Correct Answer : C
Correct answer: both the assertion and the reason are true and the reason explains the assertion
Both are true and the reason is the mechanism. Infrared activity requires the vibration to change the dipole moment. In the symmetric stretch both oxygen atoms move outward together, so the two C-O bond dipoles remain equal and opposite at every instant and the resultant stays zero. With no oscillating dipole there is nothing for the radiation to couple to, and the mode is silent in the infrared - though it appears clearly in the Raman spectrum.
A proton spectrum shows a triplet and a quartet with integrated areas in the ratio 3 to 2. The fragment present is
Your Answer : (Not Answered)
Correct Answer : B
Three protons split by two neighbours give the triplet and two protons split by three give the quartet, which is the signature of a chain ending in a methyl next to a methylene. An isopropyl group would give a doublet and a septet instead.
A binary melt at 40 per cent B separates into a solid of 10 per cent B and a liquid of 60 per cent B. The fraction that is liquid is
Your Answer : (Not Answered)
Correct Answer : D
Correct answer: 0.60
By the lever rule the liquid fraction is the distance from the overall composition to the solid, over the whole tie line: \[ \frac{40-10}{60-10} = \frac{30}{50} = 0.60. \] The arm is measured towards the phase whose amount is wanted - taking the other arm gives 0.40, which is the standard error and is offered here as a distractor.
Assertion: a high viscosity index is desirable in an engine oil. Reason: the oil must be thin enough to circulate when cold and thick enough to carry load when hot.
Your Answer : (Not Answered)
Correct Answer : B
Correct answer: both the assertion and the reason are true and the reason explains the assertion
Both are true and the reason states the requirement precisely. The engine must be started cold, when a thick oil would not reach the bearings, and must be protected hot, when a thin one would not carry load. Only an oil whose viscosity changes little between the two conditions can do both, which is exactly what a high viscosity index means.
A soluble oil cutting fluid is required to emulsify readily with water in order to
Your Answer : (Not Answered)
Correct Answer : B
Correct answer: combine water's cooling with oil's lubricity
Water is much the better coolant and oil much the better lubricant, and an emulsion delivers both from one fluid. The oil is supplied as a concentrate that must emulsify readily and stably when the operator adds water, since a poorly formed emulsion separates in the sump and delivers neither property reliably.
High temperature carbonisation of coal, at about 1000 degrees, is carried out to make
Your Answer : (Not Answered)
Correct Answer : C
Correct answer: metallurgical coke
High temperature carbonisation at about 1000 °C drives off almost all the volatile matter and leaves a hard, strong, porous coke able to bear the burden in a blast furnace - that strength is what the high temperature buys. Low temperature carbonisation at around 700 °C is the process that gives a soft domestic coke and a tar richer in the lighter oils.
A monomer of functionality two polymerises to give
Your Answer : (Not Answered)
Correct Answer : D
Correct answer: a linear chain
A bifunctional monomer can react at two points, so it links to one neighbour on each side and the growth is one-dimensional - a linear chain. Three or more reactive sites allow branching in a third direction and lead to a cross-linked network, which is how thermosets are made. Functionality is therefore what determines whether a polymerisation gives a thermoplastic or a thermoset.
Poly(vinyl chloride) requires a heat stabiliser during processing because it tends to
Your Answer : (Not Answered)
Correct Answer : B
Correct answer: eliminate hydrogen chloride
Heating PVC strips hydrogen chloride from the chain, leaving a conjugated sequence that absorbs visible light and discolours the material, and the acid released catalyses further elimination - so the degradation accelerates once it begins. Stabilisers based on metal soaps or organotins scavenge the acid and interrupt that autocatalysis, and without them PVC could not be processed at all.
Poly(ethylene terephthalate) is made from ethylene glycol and
Your Answer : (Not Answered)
Correct Answer : D
Correct answer: terephthalic acid
PET is the polyester of ethylene glycol and terephthalic acid, made by esterification with elimination of water. The rigid aromatic ring in the acid raises the melting point and the stiffness well above what an aliphatic diacid would give, which is what makes PET suitable for fibres, films and bottles. Adipic acid with the same glycol would give a soft low-melting polyester.
Galvanising is the coating of steel with
Your Answer : (Not Answered)
Correct Answer : A
Hot dipping or electrodeposition gives a layer that both excludes the environment and protects sacrificially where it is scratched. It is the commonest protection for structural steel and sheet in ordinary atmospheric exposure.
A cathodic inhibitor for a neutral aerated water may act by
Your Answer : (Not Answered)
Correct Answer : C
Sodium sulphite or hydrazine deprives the cathodic reaction of its electron acceptor and the whole process stops for want of it. In acid solutions organic amines and thiourea instead raise the hydrogen overvoltage at the cathode.
Soil corrosion of a buried pipeline is aggravated by soil that is
Your Answer : (Not Answered)
Correct Answer : B
A conductive soil lets the corrosion currents flow freely and the moisture provides the electrolyte, so resistivity surveys are used to identify the worst stretches. Differential aeration along the route sets up long-line currents in addition.
The limiting equivalent conductance of a weak acid cannot be found by extrapolation because its equivalent conductance
Your Answer : (Not Answered)
Correct Answer : A
Correct answer: rises steeply and without limit near infinite dilution
A strong electrolyte’s equivalent conductance varies linearly with the square root of concentration and can be extrapolated to zero. A weak electrolyte is barely dissociated at measurable concentrations and approaches complete dissociation only asymptotically, so its curve turns sharply upward near the axis and no extrapolation is possible. Kohlrausch’s law of independent migration supplies the limiting value instead.
A pH meter must be calibrated with standard buffers before use because the electrode's
Your Answer : (Not Answered)
Correct Answer : A
A real electrode departs from the theoretical 59 millivolts and carries an offset that changes as the glass ages, so two buffers fix both the slope and the intercept. Calibration is the largest single source of error in routine pH work.
Marks
Total number of questions : 20
Number of answered questions : 0
Number of unanswered questions : 20