# 280+ Manufacturing Technology 1 Solved MCQs

1.

## A pattern is generally made up of how many pieces?

A. 1
B. 2-3
C. 4-5
D. 6
Explanation: a pattern is basically a duplicate of the object that we intend to cast. patterns can be made up of wood, plastics or metals. a pattern is generally made up of two or three pieces, whereas it is casting which is in one piece.
2.

## How does pattern vary in size with casting?

A. pattern is larger in size
B. casting is larger in size
C. both have same size
D. size depends on other factors
Answer» A. pattern is larger in size
Explanation: patterns are duplicates of the objects we desire to cast. these patterns can be made up of plastics, metals or wood. a pattern is slightly larger in size as compared to casting because a pattern carries various allowances and the core prints.
3.

## A pattern carries which allowance for internal and external surfaces?

A. shrinkage allowance
B. machining allowance
C. distortion allowance
D. draft allowance
Explanation: draft allowance is also known by the name of tapering allowance, as the diameter of the cast goes on increasing in a trapezoidal shape from the bottom. a pattern has a draft allowance of an order of 1 and 3 degrees for external and internal surfaces respectively.
4.

## What is draft allowance also known as?

A. shake allowance
B. contraction allowance
C. taper allowance
D. rapping allowance
Explanation: none.
5.

## Machining allowance does not depend on which of the following factor?

A. solidifying contraction
B. machining method
C. shape and size of casting
D. casting method
Explanation: machining allowance does not depend on solidifying contraction as it is one of the form of shrinkage allowance. but,
6.

## How much does the distortion allowance vary?

A. 1mm to 10mm
B. 2mm to 20mm
C. 1mm to 15mm
D. 2mm to 15mm
Explanation: in distortion allowance, the amount goes on to vary from 2mm to 20mm. this allowance depends on the shape of the casting that is being used. it also depends on the size of the cast and the material that is being employed for the casting.
7.

## Ferrous metals need more allowance than non-ferrous metals.

A. true
B. false
Explanation: ferrous metals have dimensions on casting which have a larger size to provide stock than the dimensions of the casting of the non-ferrous metals.
8.

## A pattern is shaken by striking it with a wooden piece. A negative allowance is provided for this. Which allowance is it?

A. machining allowance
B. rapping allowance
C. distortion allowance
D. contraction allowance
Explanation: in rapping or shake allowance, the pattern is taken out of the mould and it is rapped or shaken, so as to free it from the adjoining sand. due to this, there may be a little increase in the size of the mould cavity.
9.

## The following figure depicts which allowance?

A. machining allowance
B. shrinkage allowance
C. draft allowance
D. shake allowance
Explanation: the pattern is being taken out of the mould without the mould cavity getting damaged. the pattern is having a tapered shape, that is, it has a tapering allowance.
10.

## Which of the following is not used for the formation of the molding sand?

A. silica sand
B. binders
D. coal
Explanation: the coal is a material which is not used in the formation of the molding sand as the particle size of the coal is high and there are chances that it will react with the possible gases that are produced during the pouring of the metal and result in casting defects.
11.

## The is responsible for the impact strength in the molding sand.

A. aggregates
B. refractoriness
C. impurities
D. permeability
Explanation: in a foundry, the molding sand
12.

## Molding sand can withstand chemical reactions on it and prove it to be beneficial for the casting formation.

A. true
B. false
Explanation: molding sand is added with chemicals to enhance properties such as permeability, compressive strength etc., however, the chemical reactions happening is not viable for the formation of the casting as it might cause explosion or severe fatal effects in the casting.
13.

## The property ensures the removal of excess sand in the mould box.

B. cohesiveness
C. green strength
D. compressive strength
Explanation: the adhesiveness is a property of molding sand to get the stick or adhere to foreign material such as sticking of molding sand with an inner wall of the molding box. hence, as the sand sticks to the box and the excess sand is removed.
14.

## Binding property of the sand increases because of the property.

A. cohesiveness
B. collapsibility
C. flow ability
D. permeability
Explanation: the cohesiveness is a property of molding sand by virtue which the sand grain particles interact and attract each other
15.

## The adhesiveness and cohesiveness are the same properties of the molding sand.

A. true
B. false
Explanation: the adhesive property refers to the sticking of the sand particles to each other so that they can take up the desired shape.
16.

## Flow ability increases with increase in the green strength.

A. true
B. false
Explanation: flowability or plasticity is the ability of the sand to get compacted and behave like a fluid. it will flow uniformly to
17.

## For melting of cast iron, which of the following furnace is used?

A. rotary furnace
B. cupola furnace
C. pit furnace
D. electric furnace
Explanation: cupola is a heavy furnace and has the capability to melt down heavy metals like cast iron. hence, the cupola furnace is mostly used to melt cast iron for casting purposes.
18.

## Why is sand bed prepared for melting of metal in Cupola furnace?

A. it provides a refractory bottom
B. it soaks the moisture from the metal
C. it conducts the heat faster and uniformly
D. none of the mentioned
Answer» A. it provides a refractory bottom
Explanation: a sand bed needs to be prepared because it provides a necessary refractory bottom for molten metal and coke.
19.

## What is the function of slag hole in a cupola furnace?

A. to tap the slag generated
B. to generate the slag
C. to allow outflow of gases
D. all of the mentioned
Answer» A. to tap the slag generated
Explanation: slag hole is a tapping hole in a
20.

## Incoming air pressure and quantity in cupola furnace are controlled by which of the following element?

A. tuyeres
B. tapping spout
C. wind box
D. blast pipe
Explanation: the air enters the cupola through the tuyers. but the air blowers in the wind box controls the requisite pressure and quantity of air coming inside.
21.

## Which of the following chemical compound, is the most common flux added to the charge in a cupola furnace?

A. coke
B. methane
C. carbon dioxide
D. limestone
Explanation: limestone (caco3) is used as flux in cupola furnace in a proportion of about 2-4% of the metal charge.
22.

## Which of the following metal has a melting point of about 1537oC and latent heat of fusion 65.0 cal/g?

A. nickel
B. copper
C. zinc
D. iron
Explanation: iron is the metal having a melting point of about 1537oc and latent heat of fusion of 65.0 cal/g. it has a mean specific heat of 0.141 cal/g-oc and heat required for melting 1 kg of iron is 1168 kj.
23.

## What is hearth in a furnace?

A. the electrodes are often called hearth
B. the walls of the furnace
C. the bowl shaped bottom of the furnace
D. the dome shaped roof of the furnace
Answer» C. the bowl shaped bottom of the furnace
Explanation: the hearth is that bowl shaped bottom of the furnace. it is made up of a high refractory material (bricked and granular).
24.

## Why are flux added to the charge ( parent metal to be melted) during melting of a metal?

A. to increase carbon content
B. to increase refractoriness
D. to remove specific oxides
Answer» D. to remove specific oxides
Explanation: the flux is a chemical substance, added to the metal while melting it to remove oxides present in the metal.
25.

## Which of the following is/are the advantage(s) of an Induction Furnace?

A. higher yield
B. cleaner melting
C. compact installation
D. all of the mentioned
Answer» D. all of the mentioned
Explanation: advantages offered by induction furnace are higher yield, faster startup, cleaner melting, natural stirring and compact installation.
26.

## Which of the following metal has a melting point of about 420oC and latent heat of fusion 26.3 cal/g?

A. nickel
B. copper
C. zinc
D. iron
Explanation: zinc is the metal having a melting point of about 420oc and latent heat of fusion of 26.3 cal/g. it has a mean specific heat of 0.101 cal/goc and heat required for melting 1 kg of zinc is 285 kj.
27.

## Which of the following metal has a melting point of about 660oC and latent heat of fusion 92.7 cal/g?

A. aluminium
C. magnesium
D. tin
Explanation: iron is the metal having a melting point of about 660oc and latent heat of fusion of 92.7 cal/g. it has a mean specific heat of 0.237 cal/goc and heat required for melting 1 kg of iron is 1022 kj.
28.

## Gas-Fired burner is used in which of the following furnace?

A. induction furnace
B. reverberatory furnace
C. cupola furnace
D. crucible furnace
Explanation: reverberatory furnace use gas- fired burner, located higher in the furnace transferring heat by radiation to the wall and roof.
29.

## What is inoculation of cast iron?

D. addition of parent metal’s ore
Explanation: inoculation of cast iron is the addition of certain silicon alloys to molten iron to produce changes in graphite distribution.
30.

## Why is inoculation done certain times during melting of cast iron?

A. to enhance its mechanical properties
B. to reduce the liquid shrinkage of metal
C. to enhance the surface finishing
D. all of the mentioned
Answer» A. to enhance its mechanical properties
Explanation: a certain amount of silicon alloys are added to the molten metal to
31.

## Which of the following is/are not used to melt material in casting(foundry) industries?

A. cupola furnace
B. induction furnace
D. crucible furnace
Explanation: all of listed are the furnaces used by metal foundry industries to melt down metal for casting purposes, except ladle furnace.
32.

## Which type of sand is used in shell moulding?

A. black sand
B. wet and fine sand
C. dry and fine sand
D. any of the sand
Answer» C. dry and fine sand
Explanation: dry and fine sans is used in shell moulding. it is completely free if clay (90-140 gfn).
33.

## Which is the most widely used resin in shell moulding?

A. phenol formaldehyde
B. ethanol formaldehyde
C. phenol
D. ethanol
Explanation: phenol formaldehyde is used as resin in shell moulding. it acts like a thermoplastic material.
34.

## Which of the following statement is true?

A. the size of the casting can be adjustable
B. the size of the casting is not limited
C. the size of the casting obtained by shell moulding is limited
D. none of the mentioned
Answer» C. the size of the casting obtained by shell moulding is limited
Explanation: the size of the casting is limited and is usually up to 200kg.
35.

## Cylinder and cylinder heads for air cooled IC engines are casted using which technique?

A. precision investment casting
B. shell moulding
C. permanent mould casting
D. die casting
Explanation: cylinders, cylinder head, automation parts, cast tooth etc are casted using shell moulding.
36.

## In precision investment casting, to make the mould the prepared pattern is dipped into a slurry. From which material is this slurry is made up of?

A. ethyl silicate
B. sodium silicate
C. both ethyl and sodium silicate
D. neither ethyl nor sodium silicate
Answer» C. both ethyl and sodium silicate
Explanation: the slurry in which prepared pattern is dipped into is made by suspending fine ceramic particles in ethyl silicate or sodium silicate.
37.

## Another name of Gravity Die Casting is?

A. centrifugal casting
B. permanent mould casting
C. precision investment casting
D. hot chamber process
Explanation: since, metal enters the mould under gravity, hence permanent, mould casting is also known as gravity die casting.
38.

## In PIC, any wax remnants are dissolved with the help of hot vapors of a solvent. Which solvent is used for this purpose?

A. ethanol
B. chlorofluorocarbon
C. trichloroethylene
D. any of the above
Explanation: before preheating of the prepared mould, any of the wax remnants are dissolved with the help of a solvent such as trichloroethylene.
39.

## Which of the following is a limitation of die casting, but is overcome in vacuum die casting?

A. the air left in the cavity when the die is closed
B. the moisture left in the cavity when the die is closed
C. the air left in the cavity when the die is open
D. the moisture left in the cavity when the die is open
Answer» A. the air left in the cavity when the die is closed
Explanation: in die casting the major problem is the air left inside the cavity when the die is closed, but in the case of vacuum die casting this air is evacuated out.
40.

## Pattern used in shell moulding is normally made up of?

A. wax
B. metal
C. wood
D. plastic
Explanation: metal is the most used material to make patterns for a process of shell moulding.
41.

## The casting process that does not require a core to produce a hollow casting is?

A. shell moulding
B. hot-chamber die casting
C. permanent mould casting
D. true centrifugal casting
Explanation: permanent mould casting is the only process that does not require cores to be used for hollow projections.
42.

## Squeeze casting method was developed in which country?

A. japan
B. india
C. america
D. russia
Explanation: russia was the country in which squeeze casting was first developed.
43.

## The tundish is a

A. pouring vessel
B. riser
C. type of core
D. machine name
Explanation: tundish is a refractory lined intermediate pouring vessel.
44.

## Which of the type of centrifugal casting methods is used to produce ‘non- symmetrical’ shaped castings?

A. true centrifugal casting
B. semi centrifugal casting
C. centrifuging
D. non centrifugal casting
Explanation: more than a single object is connected radially through a central sprue in centrifuging. but the castings need not be symmetrical always, unlike other centrifugal casting processes.
45.

## True centrifugal casting method is usually used to make

A. bent pipes
B. hollow pipes
C. bolts
D. nuts
Explanation: true centrifugal casting method is usually used to make ‘hollow pipes and tubes’.
46.

## Which of the following forces provides continuous pressure on the metal in centrifugal casting?

A. spring force
B. centrifugal force
C. gravitational force
D. frictional force
Explanation: in centrifugal casting, mould is rotated rapidly about its central axis as the metal is poured into it. because of the centrifugal force, continuous pressure is applied to the metal as it solidifies. the slag and the other inclusions being lighter gets separated from the metal and segregates toward the centre.
47.

## Which of the following methods of casting is best suited for casting of hollow pipes and tubes?

A. investment casting
B. permanent mould casting
C. die casting
D. centrifugal casting
Explanation: specifically, true centrifugal casting is generally used for the making of hollow pipes and tubes, which are axi- symmetric with a concentric hole. molten metal is accumulated at the inward surface of the mould by the rotation of the mould and then the solidification of a melt is taking place.
48.

## 5 CENTRIFUGAL CASTING

A. true
B. false
Explanation: in centrifugal casting, there is no requirement of any core for the making of the concentric hole. as the metal is always pushed outward because of the centrifugal force, application of core is eliminated. only the oxides and slag part separate from the metal and segregate at the centre.
49.

## The axis of rotation of the mould should be horizontal for the casting of long pipes in centrifugal casting.

A. true
B. false
Explanation: in centrifugal casting, the axis of rotation of the mould can be horizontal, vertical or any angle in between. generally, very long pipes are cast with a horizontal axis, whereas short pieces are more conveniently cast with a vertical axis, as it requires less area for the casting operation.
50.

## In centrifugal casting, only sand moulds can be used due to the problem of sticking of metal.

A. true
B. false
Explanation: not only sand moulds, the metallic moulds can also be used in the centrifugal casting process for large scale production. as inducing of high temperature of metallic mould can be avoided by water circulation through it and sticking problem can also be solved by casting of non-sticking materials.
51.

## In centrifugal casting, a movable pouring basin is employed for the pouring of molten metal.

A. true
B. false
Explanation: the molten metal is poured into the mould in requisite quantity through a movable pouring basin. the thickness of the pipe determined by the amount of metal poured into the mould. then after the completion of pouring, mould is rotated at its operational speed till it solidifies to form the requisite tubing.
52.

## The speed of rotation is almost double in semi centrifugal casting as compared to the true centrifugal casting.

A. true
B. false
Explanation: in semi-centrifugal casting method, complicated but axi-symmetric shapes of casting can be possible to make and this is accomplished by pouring of molten metal into the mould, which is rotated about a vertical axis. and the rotating speeds used in this process are not as high as in the case of true centrifugal casting.
53.

## Which of the following moulds or moulding is also known as sodium silicate process.

A. shell moulding
B. permanent moulding
C. slush moulding
D. co2 moulding
Explanation: carbon dioxide moulding is also known as sodium silicate process is one of the widely used processes for preparing of moulds and cores. basically, sodium silicate is used as a binder, but it binds the sand
54.

## How much percentage of sodium silicate (Na2SiO3) is added to the sand mixture in Co2 moulding?

A. 0 to 2 %
B. 2 to 6 %
C. 6 to 10 %
D. 10 to 14 %
Answer» B. 2 to 6 %
Explanation: no other things like clay, water and resins are added to the sand except sodium silicate, which reacts with the sand mix to increase the flow-ability to fill up corners and intricate contours. then the co2 is supplied to the mould and reaction takes place as follows:
55.

## How much time (in a minute) is usually required for the passing of Co2 through the mould?

A. one
B. two
C. five
D. seven
Explanation: in co2 moulding, mould of sand is hardened by passing of co2 for about one minute. the co2 gas forms a weak acid that hydrolyzes the sodium silicate (na2o, sio2) solution to form amorphous silica gel which acts as the bond and sodium silicate itself also provides some bonding action.
56.

## It is very safe to use Co2 in Co2 moulding, so it eliminates the use of any shielding apparatus.

A. true
B. false
Explanation: in co2 moulding, the process uses relatively safe carbon dioxide gas and it does not cause any of the sand disposal problems or any kind of odour while mixing and pouring. so the using of carbon dioxide gas is very safe to human operators. and so, no any equipment is required for the shielding.
57.

## Which of the following additives are added to the sand in Co2 moulding for the improvement in collapsibility of the sand?

A. copper oxide
B. wood flour
C. aluminium oxide
D. oil
Explanation: after the preparation of the sand mixture by adding sodium silicate to the
58.

## Co2 moulding process is an ideal process, where speed and flexibility is the prime requirement.

A. true
B. false
Explanation: in co2 moulding, moulds and cores of varied sizes and shapes can be formed, this is mainly achieved by the using of binder sodium silicate that can binds the sand in any shape and size, and that is further tightened by the passing of co2 gas. this makes the moulding process very fast and flexible, so this process is more economical, where speed and flexibility is the prime requirement.
59.

## Moisture from the mould can be removed by using of dryer or heater in Co2 moulding.

A. true
B. false
Explanation: in co2 moulding, water is never added while preparing a sand mixture. instead of water, sodium silicate is added to act as a binder. hence the moisture is completely eliminated from the mould. so, this process provides great dimensional tolerances and high accuracy in the production of castings.
60.

## Co2 moulding is a kind of sand moulding, but it is not economical than the green sand moulding.

A. true
B. false
Explanation: better surface finish of castings with close tolerances are produced by co2 moulding, but it is still not economical than the green sand moulding because this process uses expensive devices like co2 cylinder, hoses, regulator, hand held applicator gun or nozzle etc., and the processes in green sand moulding are simple and no expensive devices are required, due to this, green sand moulding is more economical.
61.

## Which of the following defect is not a gas defect?

A. blow holes
B. air inclusions
C. run out
D. pin hole porosity
Explanation: blow holes, air inclusions and pin hole porosity are known as “gas defects” in casting. blow holes and open blows are spherical, flattened or elongated cavities present inside the casting or on the surface of the casting. these are caused b moisture left in the mold and core. air inclusions are due to absorption of gases by the molten metal in the furnace, they cannot escape and weaken the mold during casting. these are due to high pouring temperatures. pinhole defects are a form of gas porosity. they are usually small, elongated holes at or immediately below the casting surface with the long axis of the pinhole perpendicular to the casting surface.
62.

## Which gas defect is caused by hydrogen in molten metal?

A. blow holes
B. air inclusions
C. open blows
D. pin hole porosity
Explanation: as hydrogen is such a small atom, it can diffuse rapidly once it is absorbed, creating pinholes. hydrogen being absorbed by the molten metal inside the furnace and inside the cavity. this is the main reason for the evolution of pinhole porosity.
63.

## Cuts, washes, swell, drop etc. are the examples of which of the following casting defects?

A. gas defect
B. pouring material defect
C. moulding material defect
D. metallurgical defect
Explanation: moulding material defects are caused by the characteristics of molding materials. cuts, washes, swell, drop etc. are some known examples of this type. these are caused by poor strength of moulding sand or molten metal flowing at high velocity.
64.

## When the molten metal leaks out of mould which defect occurs?

A. run out
B. misrun
C. fusion
D. drop
Explanation: a run out occurs when molten metal leaks out of the mould during pouring. this is caused by defecting moulding boxes, faulty clamping and weighing and by casting too near the edge of the box. this defect is avoided by modifying the moulding system, providing proper line and providing proper gating system.
65.

## The lower fluidity of molten material causes

A. misrun
B. cold shut
C. misrun & cold shut
D. fusion
Answer» C. misrun & cold shut
Explanation: fluidity is a very important consideration in metal casting. cold shuts and misruns can be caused by a lack of fluidity in the metal.
66.

## Defects caused by the chilling of the casting are known as?

A. hot spots
B. hot tears
C. shrinkage cavity
D. swell
Explanation: hot spots are the thick sections, those cool slower than other sections causing abnormal shrinkage. defects such as voids cracks and porosity are created at these hot spots.
67.

## During melting process flux is added to react with impurities to form?

A. cavity
B. slag
C. cold shut
D. blow holes
Explanation: slag is said to be refuse produced as a result of melting nonferrous material which have a high melting point, it is
68.

## Which defect is caused due to the conversion of moisture to steam because of the heat of molten metal?

A. blow holes
B. open blows
C. air inclusions
D. cold shut
Explanation: blow holes are entrapped gases, which are formed as a result of gases from mould, molten metal and stream sand. further these are caused due to the conversion of moisture to steam because of the heat of molten metal.
69.

## Defect which occurs due to the solidification of casting is known as?

A. swell
B. misrun
C. metal penetration
D. shrinkage cavity
Explanation: shrinkage cavity is a void on the surface of the casting caused mainly due to uncontrolled and haphazard solidification of the metal. these can be of two types,
70.

## The direction of rmf when a single phase supply is given to stator of three phase induction motor is?

A. zero
B. ns
C. 2ns
D. -ns
Explanation: there will be no rmf generated as a single phase is only fed to the three phase of induction motor.
71.

## The direction of rmf when a three phase supply is given to stator of three phase induction motor is?

A. zero
B. ns
C. 2ns
D. -ns
Explanation: there will be rotating magnetic field will be produced causing the emf to be induced and the current will flow in the rotor at a speed of synchronous speed.
72.

## Two three phase induction motors A and B are identical in all respects except that motor A has a larger air-gap than motor B. Which motor will have more no load current?

A. a
B. b
C. both a and b
D. neither a nor b
Explanation: as the air gap of motor a is more, it will require more flux to excitation and so the no load current.
73.

## Two three phase induction motors A and B are identical in all respects except that motor A has a larger air-gap than motor B. Which motor will have poorer power factor?

A. a
B. b
C. both a and b
D. neither a nor b
Explanation: due to larger air gap of motor a, it will need more of exciting current. so the no load angle will increase and power factor will deteriorate.
74.

## Two three phase induction motors A and B are identical in all respects except that motor A has a larger air-gap than motor B. Which motor will have better full-load power factor?

A. a
B. b
C. both a and b
D. neither a nor b
Explanation: at full load conditions, the excitation current is not very high and so the power factor improves.
75.

## A three phase induction motor is sometimes calles a generalized transformer in so far as voltage and frequency transformation has been concerned. How a three phase induction motor operates when rotor frequency is equal to stator frequency?

A. it will not operate
B. it will operate as induction motor only
C. it will operate as induction generator
D. it will operate in braking mode
Answer» A. it will not operate
Explanation: as the rotor and stator
76.

## and the rotor current I2 are zero at

A. ns
B. 2ns
C. zero
D. slip of 50%
Explanation: the rotor emf and current are zero at the speed of synchronous speed of the machine.
77.

## If use auto transformer method starting to start an induction motor to replace star-delta method, then the required tapping on the transformer will be

A. 57.73%
B. 86.7%
C. 57%
D. 66.66%
Explanation: k = 1/1.73 = 57.73%.
78.

## The starting method for a 3-phase squirrel-cage induction motor which is inferior in view of poor starting torque per ampere of line current drawn is?

A. series-inductor method of starting
B. direct-on-line starting
C. auto-transformer method
D. star-delta method
Answer» A. series-inductor method of starting
Explanation: due to inductor method, reactance increases and the starting torque decreases.
79.

## volts, I = 200 A, and the cross-sectional area of the weld bead is 30 mm2. Estimate the welding speed if the workpiece and electrode are made of (a) aluminum, (b) carbon steel, and (c) titanium. Use an efficiency of 75%.

A. 35 mm/s
B. 34.5 mm/s
C. 36 mm/s
D. 46 mm/s
Explanation: for aluminum, the specific energy required is u = 2.9 j/mm3 therefore,
80.

## Upon which of the following parameters does the current intensity in arc welding depend?

A. stability of arc
B. electrode diameter
C. gap between the electrode and parent metals
D. thickness of parent metals
Explanation: electrodes for consumable arc- welding processes are classified according to the following properties:
81.

## In which of the following welding processes we use two non-consumable electrodes?

A. mig
B. tig
C. atomic hydrogen
D. submerged arc
Explanation: non consumable electrodes are the ones that are not consumed during the process of welding. gtaw (gas tungsten arc welding)/tig (tungsten inert gas welding), ahw (atomic hydrogen welding), caw (carbon arc welding) processes use non-consumable electrodes.
82.

## Which of the following brazing process is good for mass scale joining?

A. furnace
B. induction
C. dip
D. torch
Explanation: furnace brazing is a semi- automatic used widely in industries and are best suited to large scale production operations.
83.

## For grey cast iron, which of the following welding methods is preferable?

A. mig
B. submerged arc
C. gas flame
D. electric arc
Explanation: as the percentage of carbon in grey cast iron is less, therefore mig welding is preferable.
84.

## Due to which of the following reasons, flux is not used in atomic hydrogen welding?

A. the burning hydrogen shields the molten metal
B. two electrodes are coated which gradually release the flux
C. the filler rod is coated with flux
D. one of the two electrodes is coated which releases the flux
Answer» A. the burning hydrogen shields the molten metal
Explanation: separate flux/ shielding gas is not required in atomic hydrogen welding. the
85.

## In resistance welding, between the electrodes, the nature of current and voltage parameters being used?

A. high current, high voltage
B. low current, high voltage
C. low current, low voltage
D. high current, low voltage
Answer» D. high current, low voltage
Explanation: high current produces more heat. when we use a low voltage power source, it allows a welder to have some reasonable over the small lighting bolts we use to fuse metal together.
86.

## Which of the following welding process in which heat is produced for welding by a chemical reaction?

A. resisting welding
B. thermit welding
C. forge welding
D. gas welding
Explanation: the thermite process is a chemical reaction in which a metal oxide (preferably molten) is displaced by another molten metal which is more reactive than the metal in the metal oxide, releasing a lot of heat. example:
87.

## The maximum diameter of electrodes being used in submerged arc welding?

A. 30 mm
B. 20 mm
C. 15 mm
D. 10 mm
Explanation: a consumable electrode can be used by the submerged arc welding which is a loop of bare round wire with 1.5 mm to 10 mm diameter. it can be fed routinely throughout the welding gun, and the submerged arc welding electrode composition depends on the welded material.
88.

## Which of the following gases are used in Tungsten inert gas welding?

A. helium and neon
B. hydrogen and oxygen
C. argon and helium
D. carbon dioxide and hydrogen
Explanation: in the tig welding process the arc is formed between a pointed tungsten electrode and the workpiece in an inert atmosphere of argon or helium.
89.

## Which of the following materials necessitates preheating in welding?

A. copper
B. aluminium
C. cast iron
D. stainless steel
Explanation: as the weldability of cast iron usually decreases as the amount of free carbon in cast iron increases, so it is preheated to a dull red and then welded.
90.

## Which of the following is also called “gas welding”?

A. oxy fuel gas welding
B. metallic welding
C. arc welding
D. fuel gas welding
Answer» A. oxy fuel gas welding
Explanation: gas welding is also known as oxy fuel gas welding. in gas welding, fuel gases are used to generate high amount of heat and melt the metal.
91.

## How many types of flames are there in welding?

A. 1
B. 2
C. 3
D. 4
Explanation: there are three basic flame types: neutral (balanced), excess acetylene (carburizing), and excess oxygen (oxidizing) as shown below.
92.

## In which of the following type of flame, oxygen is in excess proportion with acetylene?

A. neutral flame
B. oxidizing flame
C. carburizing flame
D. both oxidizing flame and carburizing flame
Explanation: oxidizing welding flames are produced when slightly more than one volume of oxygen is mixed with one volume of acetylene. oxidizing welding flames are commonly used to weld zinc, copper, manganese steel, cast iron, etc.
93.

## In which of the following type of flame, oxygen is deficient in proportion with acetylene?

A. neutral flame
B. oxidizing flame
C. carburizing flame
D. both oxidizing flame and carburizing flame
Explanation: the carburizing flame has excess acetylene then oxygen. reducing flame is used for the welding of low carbon and alloy steel.
94.

## For brazing, soldering and flame hardening which of the following flame is used?

A. neutral flame
B. oxidizing flame
C. carburizing flame
D. both oxidizing flame and carburizing flame
Explanation: for brazing, soldering and flame hardening carburizing flame is used.
95.

## The inner cone of the flame in welding has the following nature?

A. highest temperature
B. coldest temperature
C. moderate temperature
D. uncertain
Explanation: the inner cone of the flame has the highest temperature (3500°c). the outer flame has the lowest temperature.
96.

## The oxy acetylene gas welding is a type of?

A. endothermic reaction
B. exothermic reaction
C. neutral reaction
D. both endothermic reaction and exothermic reaction
Explanation: the oxy acetylene gas welding is a type of exothermic reaction. 1 mole of acetylene can produce kj/mol of heat.
97.

## The chemical formula of acetylene is?

A. c2h4
B. c2h6
C. c2h5oh
D. c2h2
Explanation: the chemical formula of acetylene is c2h2. 1 mole of acetylene can produce kj/mol of heat.
98.

## Amount of time during which the transformer will be used for welding under normal loading condition is known as?

A. hold time
B. off time
C. weld time
D. duty cycle
Explanation: amount of time during which the transformer will be used for welding under normal loading condition is known as the duty cycle.
99.

## Amount of voltage required to generate the arc under no load condition is called?

A. open circuit voltage
B. closed circuit voltage
C. short circuit voltage
D. arc voltage