Your Answer : (Not Answered)

Correct Answer : B

Emission standards act on one source at a time while the ambient standard governs the combined result. Where the load exceeds what the area can absorb, a cluster-level plan is needed rather than a finding against any one operator.

Your Answer : (Not Answered)

Correct Answer : C

Kyoto set binding targets for developed countries alone, whereas Paris asks every party to submit nationally determined contributions. The shift from imposed targets to pledged ones is the essential difference between them.

Your Answer : (Not Answered)

Correct Answer : A

Correct answer: Record emissions from a source in real time for compliance

A continuous emission monitoring system is installed in the stack and reports concentrations continuously, typically transmitting them to the regulator.

The gain over periodic manual sampling is coverage: a stack test measures a few hours a year, and a plant can be operated well during it, whereas continuous monitoring records what happens the rest of the time. It measures the source, not the surrounding air, which is what ambient monitoring stations at the boundary do.

Your Answer : (Not Answered)

Correct Answer : D

Correct answer: Removal of radon gas

Every row of the table addresses either particles or gases that adsorb. Coarse and fine filters and HEPA all capture particulate, and activated carbon adsorbs organic vapours and odours.

Radon fits neither. It is a noble gas, so it is not adsorbed usefully by carbon, and it is a gas, so no particulate filter touches it. That is precisely why radon is controlled by preventing entry - sealing and sub-slab depressurisation - rather than by anything in a ventilation plant's filter bank.

Your Answer : (Not Answered)

Correct Answer : A

The chain begins with moisture and a cold surface, and every practical control breaks it early by reducing moisture generation, ventilating it away or raising the surface temperature. Treating the visible colonies alone leaves the chain intact.

Your Answer : (Not Answered)

Correct Answer : D

Correct answer: Poisons catalysts and forms sulphate particulate

Sulphur attacks aftertreatment twice over. It adsorbs onto the precious metal sites and suppresses catalytic activity, and it is oxidised to sulphate which condenses and is weighed as particulate.

Both effects made low sulphur fuel a precondition rather than a refinement: particulate filters and reduction catalysts could not be introduced until the fuel supply was cleaned up, which is why sulphur limits and emission standards advanced in step. It does not affect atomisation or cetane appreciably.

Your Answer : (Not Answered)

Correct Answer : A

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the reason is the mechanism. Above roughly 50 per cent relative humidity, water condenses in the micropores of the carbon and occupies sites that would otherwise hold the organic vapour, so the working capacity falls - by half or more in a saturated stream. The remedy is to condition the gas first, by cooling and condensing the moisture out or by warming it to lower the relative humidity.

Your Answer : (Not Answered)

Correct Answer : C

Adsorption capacity rises as the temperature falls and as competing molecules are removed, so cooling and drying the stream helps directly. The other three each occupy or weaken the sites the target molecule would otherwise use.

Your Answer : (Not Answered)

Correct Answer : A

The gas must be soluble in the chosen liquid, and the driving force is the difference between the partial pressure in the gas and the equilibrium pressure over the liquid. Packed and plate towers both exist to maximise the area over which that transfer takes place.

Your Answer : (Not Answered)

Correct Answer : D

A thin conductive film on the particle surface brings the resistivity back into the workable window and restores collection. It became common when low sulphur coals were adopted and precipitator performance fell away unexpectedly.

Your Answer : (Not Answered)

Correct Answer : A

Correct answer: A is false but R is true

The assertion is false. An annual mean may not be reported from any data capture rate; a minimum - commonly 90 per cent of valid hours, excluding routine calibration and maintenance - must be met before the mean is considered representative.

The reason is true, and it is in fact why the assertion is false. Missing periods are rarely random: instruments fail in the extremes of heat, cold and humidity that also produce the highest concentrations, so gaps tend to remove exactly the episodes that matter most. A mean computed over the surviving hours is therefore biased low rather than merely less precise.

Your Answer : (Not Answered)

Correct Answer : B

Correct answer: The gravimetric method or an equivalent

Compliance with a limit value must be shown using the reference method or a method demonstrated equivalent to it. The table marks high volume gravimetric as the reference, and beta attenuation and TEOM as equivalent only if that demonstration has been made. So the defensible choice is the gravimetric method, or an instrument that has passed an equivalence demonstration.

A TEOM is acceptable only once that demonstration exists, which is why naming it alone is wrong. Optical scattering is marked indicative only and cannot support a compliance judgement, and "any of them" ignores the equivalence requirement entirely.

Your Answer : (Not Answered)

Correct Answer : C

Correct answer: The colour of the station housing

The colour of the housing has no bearing on the validity of the mean. It may affect internal temperature slightly, but analysers are temperature-controlled and the measurement does not depend on the shade of the paint.

The other three are exactly what determines whether an annual mean can be defended. The data capture rate decides whether enough of the year was actually measured; traceability of the span gas fixes whether the readings are on the right scale at all; and siting decides what the station represents, since a mean from a badly sited station is precise but describes the wrong air.

Your Answer : (Not Answered)

Correct Answer : A

Correct answer: 1584 m³

The two conversions - minutes to hours and hours to a day - are where the arithmetic usually goes wrong.

Your Answer : (Not Answered)

Correct Answer : C

Correct answer: A breaking inversion brings a plume down

This is the true statement. Fumigation is precisely the rapid downward mixing that occurs when a nocturnal inversion breaks up and the growing unstable layer reaches a plume travelling in the stable air above.

It therefore occurs in the morning, in the hour or so after sunrise, not in the late evening - the evening is when the inversion forms. Far from dispersing pollution well, it produces some of the highest short-term ground level concentrations recorded, because material accumulated overnight arrives at once. Removal of a plume by rain is wet scavenging, a quite separate process.

Your Answer : (Not Answered)

Correct Answer : A

Correct answer: Z, where the inversion suppresses mixing

Occasion Z is the inversion: the temperature rises from \( 8.0 \) degrees at the surface to \( 10.5 \) degrees at \( 500 \) m, giving the negative lapse rate of \( -5.0 \) degrees per kilometre shown in the table. Vertical motion is strongly suppressed, so an emission from a low stack is trapped in a shallow layer near the ground and concentrations build.

Occasion W, with a lapse rate of \( 11.0 \) exceeding the adiabatic \( 9.8 \), is superadiabatic and mixes most vigorously, giving the lowest concentrations. X is neutral and Y mildly stable - both disperse far better than an inversion, in which the atmosphere actively opposes the vertical motion that dilution requires.

Your Answer : (Not Answered)

Correct Answer : B

Correct answer: 0.5

Ground level concentration is inversely proportional to wind speed, since \( u \) appears once in the denominator of the Gaussian plume equation. Doubling the wind speed therefore halves the concentration:

\[ \frac{C_8}{C_4} = \frac{u_4}{u_8} = \frac{4}{8} = 0.5 \]

The emission rate of \( 80 \) g/s is unchanged and does not enter the ratio. A factor of \( 0.25 \) would follow from an inverse-square dependence, which is not the case here; the wind dilutes in direct proportion to how fast it carries the plume away.

Your Answer : (Not Answered)

Correct Answer : D

The surface cools faster than the air above it, so the lowest layer becomes the coldest. It breaks up soon after sunrise as the ground warms again, which is why morning traffic emissions are trapped and afternoon ones are not.

Your Answer : (Not Answered)

Correct Answer : B

Correct answer: It reaches the alveolar region

The fine fraction is most damaging because it penetrates to the alveolar region, where gas exchange occurs and where there is no mucociliary escalator to remove it - hence the clearance time of weeks to months shown in the table. Prolonged residence at the gas exchange surface allows inflammation to develop and permits soluble and ultrafine components to cross into the circulation.

Coarse particles are trapped higher up and cleared within hours. Fine particles are the least visible individually and settle most slowly, not the reverse.

Your Answer : (Not Answered)

Correct Answer : C

Correct answer: 1, 2, 3, 4

Deposition proceeds inward as particle size falls. The nasopharyngeal region (1) captures the coarsest particles by impaction on the turbinates. The tracheobronchial region (2) captures intermediate sizes as the airway branches.

The alveolar region (3) receives the fine fraction, small enough to follow the air stream to the gas exchange surface, where sedimentation and diffusion deposit them. The finest particles can cross the alveolar membrane into the systemic circulation (4) - which is how ultrafine particulate reaches organs remote from the lung.