Answer: a [Reason:] Water gets polluted by submerged vegetation mineral deposits, presence of algae, Leaves, twigs, logs under water decay and generates bad smelling gases. Thermal stratification and depletion of oxygen in lower strata generate harmful gases such CO₂ which pollute the water.

Answer: b [Reason:] Water containing H₂S, CO₂ and CH₂ are highly corrosive to dam structure. H₂SO₄ formed by oxidation of H₂S attack the cement and disintegrate the concrete. These gases increase the solubility of soil and rocks. Structures, metallic piping and penstock are also affected.

Answer: a [Reason:] Presence of Corrosive gases like H₂S and SO₂ does affect the voltage drop at brush contacts in generator leading to poor commutation. Silver contacts of relays get blackened and lead to high contact resistance and failure of relay occurs.

Answer: b [Reason:] Sediments in the aquatic ecosystem are analogous to soil in the terrestrial ecosystem as they are the source of substrate nutrients, and micro- and macro flora and -fauna that are the basis of support to living aquatic resources.

Answer: a [Reason:] The basic requirement of a hydroelectric power station is a reservoir where large quantity of water is stored during flood season and used during dry season. The reservoir is generally built of constructing dam across river.

Answer: a [Reason:] The water from reservoir is drawn by the fore bay through an open canal or tunnel. The water from fore bay is supplied to water turbine through penstock which is located at much lower level than the height of water in reservoir.

Answer: c [Reason:] Trash rack is used to prevent the entry of debris which might damage the Wicket gate and turbine. It is a wooden or metal structure and is supported by masonry, that prevents waterborne debris from entering into penstock which than connects to turbine.

Answer: c [Reason:] A pipe between the surge tank and prime mover is known as penstock. It is made of steel through reinforced concrete. Cast iron is used for small plants. The intake of penstock at the dam or fore bay of canal should be positioned such that it always provides adequate water even at low level.

Answer: a [Reason:] Buried penstocks are used in cold climates where freezing is expected. types of penstocks have shorter life period. A buried penstock will not be subjected to the problem of harmonic vibrations sometimes associated with the traditional penstock.

Answer: d [Reason:] Exposed penstocks are less expensive and have a longer life. Their inspection and maintenance is easier. Penstocks are not covered because exposed pipes are easily accessible. The water flow rate is 2, 4, and 7 m/s in low, medium and high head power plants respectively.

Answer: a [Reason:] Spillway is a safety valve for a dam to discharge major floods without damage to dam. It keeps the reservoir level below some predetermined maximum level. Spillway ensures that water does not overflow and damage or destroy the dam.

Answer: d [Reason:] Surge tank is introduced between the dam and power house nearest to the power house and preferably on the high ground to reduce the height of tower to provide better regulation of water pressure in the system during variable load condition.

Answer: a [Reason:] If the head of water available is above 100m, the plant is known as a high head plant. IN this head, water available for producing electricity is very high and it can extend to 1000 meters. These are most commonly constructed hydro plants.

Answer: b [Reason:] If the water available is more than 30m but less than 100m, than this type of plant is known as medium head plant. Water stored in fore bay is conveyed to the turbine through penstocks. In these plants the river water is tapped off to a fore bay on one bank of rive.

Answer: a [Reason:] Low head hydro electric power plant is also known as canal power plant. The dam in this type of power plant is of very small head may be even few meters only. The low head type of power plants cannot store water.

Answer: b [Reason:] Pumped storage plants supply the peak load for the base power plants and pump all or a portion of their own water supply. The plant contains a tail water pond and a head water pond connected by a penstock.

Answer: a [Reason:] Pumped storage plants can be used with hydro, steam and IC engines. The generating pumping unit is at the lower end. During off peak hours some of the surplus electric energy generated by the base plant is utilized to pump water from tail water pond into the head water pond.

Answer: b [Reason:] Modern power plants use Francis turbine. Francis turbine is a water turbine developed by James Francis. It is an inward flow reaction turbine that combines radial and axial flow concepts. These are primarily used for electric production.

Answer: d [Reason:] Run-off river power plants can be with or without pondage. A runoff river plant without pondage has no control over river flow and uses water as it comes. The runoff river plant with pondage may supply base load power.

Answer: b [Reason:] The surge tank controls the water when the load on the turbine decreases. The excess water is stored in the surge tank and hence the pressure variations in the penstock are taken care of preventing water hammer.

Answer: a [Reason:] For moderate heads butterfly valves are preferred. Gate valves are used to regulate the flow. This valve is used both as intake gate and as turbine valve. It helps inspection without dewatering the penstock line.

Answer: a [Reason:] Needle valves are used in high head installations. The needle valve consists of three water filled chambers A, B and C in which hydraulic pressures can be varied. The valves are opened and closed by varying the pressures in these chambers.

Answer: c [Reason:] With stringent air quality restriction by the governments, majority of power plants in the world use electrostatic precipitators (ESP’s) for dust removal. An ESP can handle large volumes of flue gases accompanied low pressure drop and high collection efficiency (99.5%). It facilitates easy removal of dust particles.

Answer: b [Reason:] When the high voltage is applied, it generates a unidirectional non uniform electric field having greater magnitude at the discharge electrodes. This result in a blue luminous glow called corona around them. This corona is an indication of negatively charged ionized gas molecules which travel from discharge electrodes to grounded collection electrodes.

Answer: b [Reason:] The consumption of coal and its cost has major important once as coal forms the basic ingredient of the thermal power plant. Weighment of coal is essential for getting optimum plant efficiency at reduced cost using weighers.

Answer: b [Reason:] Mechanical weigher is commonly used all over world. This based on mechanical principle. This works on a lever system mounted on knife edges and bearings that connected to a resistant like a spring or pendulum. The resultant value obtained by multiplication of load and speed values is displayed by a digital counter.

Answer: a [Reason:] The pneumatic weighers use a pneumatic transmitter weigh head and the corresponding air pressure determined by the load applied and is transmitted to the weight indicating receiver may be used where electronic system is not permitted for use.

Answer: c [Reason:] The operation is based on load cell principle. The load cells produce voltage signals proportional to the applied load. This system maintains high accuracy in measurement. Its performance is affected by temperature, noise, dust and humidity of the air.

Answer: c [Reason:] Nuclear weighing system operates on gamma ray, Works on gamma rays absorption principle. A radio-active source located in the source head emits gamma rays which pass through the material on the conveyor to the detector.

Answer: c [Reason:] Main disadvantage of the nuclear weighing machine is that its accuracy depends on a consistent speed of material movement and the condition of the detectors since this should be kept clean at all times as otherwise absorption value of gamma-rays will be affected.

Answer: d [Reason:] The process of burning fuels in presence of oxygen is called combustion. Due to the presence of combustible elements like carbon (C), hydrogen (H) and sulfur (S), fuels burn in presence of oxygen and generate heat from the fuels.

Answer: c [Reason:] The minimum temperature at which a substance begins to burn is called ignition temperature. No substance can catch fire unless it is heated up to a certain minimum temperature. The ignition of every substance is definite. For example, the ignition temperature of white phosphorous is 35¬¬¬oC. It means, white phosphorous starts burning only if it is heated up to 35oC.

Answer: c [Reason:] The substance which helps in combustion of fuels is called supporter fuels/combustible elements. For example, oxygen is a supporter of combustion because in the absence of oxygen fuels cannot burn.

Answer: b [Reason:] For complete combustion of fuels, it is necessary to supply sufficient amount of air. If air supplied is not sufficient then combustion will be incomplete. This means carbon in the fuel burns to produce carbon monoxide (CO) instead of carbon dioxide (CO₂), and thus reducing the amount of oxygen required and amount of heat generated.

Answer: b [Reason:] Based on molecular weight, 12kg of carbon combines with 32kg of oxygen forming 44kg of carbon dioxide.
i.e., 12kg of C + 32 kg of O₂ => 44kg of CO₂
1kg of C + 8/3kg of O₂ => 11/3kg of CO₂
Reaction type: synthesis.

Answer: c [Reason:] Balanced equation: 2C + O₂ => 2CO [Synthesis reaction]
Oxygen is left in excess, based on the molecular weight, 24kg of carbon combines with 32kg of oxygen forming 56kg of carbon monoxide
24kg of C + 32kg of O₂ => 56kg of CO
1kg of C + 4/3kg of O₂ => 7/3kg of CO.

Answer: a [Reason:] Based on molecular weight, 56kg of carbon monoxide combines with 32kg of oxygen forming 88kg of CO₂
Balanced equation: 2CO + O2 => 2CO₂
56kg of CO + 32kg of O₂ => 88kg of CO₂
1kg of CO + 4/7kg of O₂ => 11/7kg of CO₂.

Answer: d [Reason:] Based on molecular weight, 32kg of sulfur combines with 32kg of oxygen forming 36kg of water.
Balanced equation: 2H₂ + O₂ => 2H2O
4kg of H₂ + 32kg of O₂ => 36kg of H₂O
1kg of H₂ + 8kg of O₂ => 9kg of H₂O.

Answer: b [Reason:] Based on molecular weight, 32kg of sulfur combines with 32kg of oxygen forming 64kg of SO₂
S + O₂ => SO₂
32kg of S + 32kg of O₂ => 64kg of SO₂
1kg of S + 1kg of O₂ => 2kg of SO₂.

Answer: a [Reason:] Since the invention of diesel engine, diesel engine plants are finding increased application as either continuous or peak load source of power generation. Due to economy of operation DG plants are used to generate power in the range of 1 to 50MW capacity.

Answer: b [Reason:] DG plants are more efficient than any other heat engine of comparable size. It is available at very short delivery times and can be started quickly and brought into service. It can burn fairly wide range of fuels.

Answer: c [Reason:] Air filter removes the dust from air before entering the engine. Air actually contains oxygen which supports the combustion inside the engine chamber. And also helps in moving/taking out the exhaust fumes which are produced after combustion.

Answer: d [Reason:] Supercharger increases the pressure of air at engine inlet and hence increases engine power. They are usually driven by the engines. It usually situated after the air filter. The power for supercharger can be provided by mechanical means of belt, gear, shaft or chain connected to engine’s crankshaft.

Answer: c [Reason:] The system includes water circulating pumps, cooling towers are spraying ponds and water filtration or treatment plant. The purpose of cooling system is to ensure the life of cylinder by extracting the heat developed from the engine cylinder walls and hence keeping the temperature within the safer range.

Answer: c [Reason:] The system includes oil pumps, oil tanks coolers and connecting pipes. The system reduces the friction between the moving parts and hence reduces wear and tear. Lubricating oil also controls the temperature at mating point.

Answer: a [Reason:] The governing engine maintains constant speed of the engine irrespective of the load on plant. This is done by varying the fuel supplied to the engine. It could be very be really impractical and dangerous to run an engine without the governor or speed control mechanism and could lead to accidents such as collision or grounding.

Answer: b [Reason:] The fuel oil may be delivered at the plant side by trucks, railroad tank cars or barge and tankers. From tank truck the delivery is done using the unloading facility to main storage tanks. This fuel is then transferred by pumps to small service storage tanks know as engine day tanks.

Answer: c [Reason:] The minimum storage capacity of at least a month’s requirement of fuel is generally kept in bulk. However, when the advantage of seasonal fluctuations in cost of oil is to be availed, it may be necessary to provide storage for a few months requirement.