Multiple choice question for engineering
Set 1
1. Which gas is used for the removal of oxygen layer formed on molten iron?
a) Hydrogen
b) Oxygen
c) Carbon dioxide
d) Chlorine
Answer
Answer: b [Reason:] In oxygen cutting method, under considerable amount of pressure, when a jet of oxygen gas is made to blow on the particles of molten iron oxide, the oxygen layer present on the molten iron gets removed.
2. Up to what amount of carbon content in steels, can they be treated by oxygen cutting?
a) 0.3%
b) 0.2%
c) 0.7%
d) 0.4%
Answer
Answer: c [Reason:] For a steel to be treated by oxygen cutting process, the carbon content that should be available in terms of percentage composition is around 0.7%, that is, the steel that can be treated by this process is a high alloy steel.
3. Up to what temperatures are high alloy steels heated before treating them by oxygen cutting?
a) 675°C
b) 725°C
c) 775°C
d) 825°C
Answer
Answer: a [Reason:] In oxygen cutting process, not all steels can be treated by this method. Only high alloy steels can be treated by this method. These steels need to be preheated before oxygen cutting. The temperature range up to which these steels are preheated is about 650°C to 700°C.
4. What are the number of opening available in the cutting torch used in oxygen cutting process?
a) 4
b) 5
c) 6
d) 7
Answer
Answer: d [Reason:] Just like any other gas welding equipment, the welding torch gets substituted by a cutting torch in oxygen cutting process. The total number of openings available in the torch are six, with a large opening at the center, making the count to seven.
5. What is the maximum oxygen pressure that can be applied to steel?
a) 13 atm
b) 14 atm
c) 15 atm
d) 16 atm
Answer
Answer: b
6. What is the minimum oxygen pressure that can be applied to steel?
a) 3 atm
b) 4 atm
c) 5 atm
d) 6 atm
Answer
Answer: a [Reason:] In oxygen cutting process, not all steels can be treated by this method. Only high alloy steels can be treated by this method. The pressure supply of oxygen should not be low, as it may lead to formation of slag on the bottom of the cut. The minimum oxygen pressure that can be applied to steels is 3 atmospheres or 300 kN/m2.
7. What is the initial oxygen pressure provided through the lance?
a) 1 atm to 2 atm
b) 2 atm to 3 atm
c) 3 atm to 4 atm
d) 4 atm to 5 atm
Answer
Answer: a [Reason:] In oxygen lance cutting, jet of oxygen is passed through steel pipes, and by doing this, holes are produced. For doing this, the jet of oxygen is passed through the lancer under the pressure of 1 atm to 2 atm.
8. What should the outer diameter of a thick-welled lance be, for having good results?
a) 13 mm to 15 mm
b) 15 mm to 17 mm
c) 17 mm to 19 mm
d) 19 mm to 21 mm
Answer
Answer: c [Reason:] In oxygen lance cutting, when the lance is made up of a thick wall, with its outer diameter of 17 mm to 19 mm, and possessing an inner diameter of 8 mm to 6 mm, respectively, then good results can be obtained.
9. Cast irons are best treated using oxygen cutting process.
a) True
b) False
Answer
Answer: b [Reason:] Cast irons cannot be treated using oxygen cutting process. The reason being that, the melting point of cast irons is a lot lower than its ignition temperature. The same cannot be said for high alloy steels.
10. Oxygen cutting process can be applied to metals having melting point higher than their oxidization temperature.
a) True
b) False
Answer
Answer: b [Reason:] It can be counted among one of the drawbacks of oxygen cutting process, that the metal which is to be treated must have its oxidizing temperature higher than its melting temperature, otherwise the metal would get melted before getting oxidized.
Set 2
1. At what temperature, does fusion welding takes place?
a) 850°C
b) 900°C
c) 950°C
d) 1000°C
Answer
Answer: b [Reason:] The process of fusion welding can be used for joining metal to a metal or a metal can be joined to a ceramic. For the joining of this process, a temperature of 900°C is provided for the approach.
2. Which of the following is not a type of diffusion welding?
a) Gas-pressure welding
b) Vacuum fusion welding
c) Eutectic fusion bonding
d) Eutectoid fusion welding
Answer
Answer: d [Reason:] Diffusion welding is has three basic techniques which are incorporated by it. These three basic techniques are, gas – pressure welding, vacuum fusion welding and eutectic fusion welding.
3. What is the minimum frequency used in ultrasonic welding?
a) 10,000 Hz
b) 20,000 Hz
c) 30,000 Hz
d) 40,000 Hz
Answer
Answer: b [Reason:] The process of ultrasonic welding is mainly used for the joining of similar metals or dissimilar metals using vibration energy, by way of high frequency. The minimum frequency needed for this purpose is 20,000 Hz.
4. What is the maximum frequency used in ultrasonic welding?
a) 30,000 Hz
b) 40,000 Hz
c) 50,000 Hz
d) 60,000 Hz
Answer
Answer: d
5. In what conditions are the parts kept before welding in ultrasonic welding method?
a) Low static pressure
b) High static pressure
c) Low moving pressure
d) High moving pressure
Answer
Answer: a [Reason:] In ultrasonic welding method, the parts which are to be joined, are kept clamping to one another in between of supporting member and the welding tip. This clamping is done at a low static pressure.
6. What is the maximum thickness that can be welded in ultrasonic welding?
a) 1.8 mm
b) 2.1 mm
c) 2.3 mm
d) 2.5 mm
Answer
Answer: d [Reason:] Weldings such as spot welding or continuous seam welding can be done through ultrasonic welding. The maximum thickness that can be achieved varies depending on the metal. The maximum thickness can be that can be welded is 2.5mm.
7. Electric currents are passed is ultrasonic welding.
a) True
b) False
Answer
Answer: b [Reason:] In ultrasonic welding method, the parts which are to be joined, are kept clamping to one another in between of supporting member and the welding tip. In doing this, no current is required to be passed through the metal, and usually, no heat is needed for this too.
8. What is the minimum thickness that can be welded in ultrasonic welding?
a) 0.58 mm
b) 0.21 mm
c) 0.38 mm
d) 0.92 mm
Answer
Answer: c
9. Which of the following is not a factor for explosive welding?
a) High relative velocity
b) Less amount of plastics
c) Proper orientation
d) High pressure
Answer
Answer: b [Reason:] While considering for explosive welding, the factors that one needs to understand is that, there has to be high relative velocity. There should be proper orientation and it needs to be kept under high amount of pressure.
10. ‘α’ is the angle between target plate and flyer plate.
a) True
b) False
Answer
Answer: a [Reason:] The workpiece which has its position fixed is called as the target plate and the other plate is called as flyer plate. The distance between the two plates is denoted by ‘d’ and the angle between them is denoted by ‘α’.
Set 3
1. Why is carbon used in carbon arc welding?
a) Generation of more heat at electrode tip
b) Generation of less heat at electrode tip
c) Provides coating
d) Fixed polarity is maintained
Answer
Answer: b [Reason:] Carbon is used in carbon arc welding, at the negative terminal of the cathode. The reason for employing carbon at the negative terminal is that, a lesser amount of heat is generated at the electron tip than at the workpiece.
2. What is the temperature at the negative terminal in carbon arc welding?
a) 3000°C
b) 3100°C
c) 3200°C
d) 3300°C
Answer
Answer: c
3. The process of carbon arc welding is not used for which of the following material?
a) Copper
b) Bronze
c) Aluminium
d) Iron
Answer
Answer: d [Reason:] The process of carbon arc melting is widely used for copper and copper alloys, hence bronze and brass are treated by this method. Aluminium can also be treated likewise, but not iron metal.
4. Which gas is used as a protection in carbon arc welding?
a) Carbon dioxide
b) Carbon monoxide
c) Carbon tetra fluoride
d) Methane
Answer
Answer: b [Reason:] In carbon arc welding, there has to be a protection to be provided to the molten weld. This protection is provided in the form of an envelope by using a long arc giving carbon monoxide gas.
5. What is the temperature at the positive terminal in carbon arc welding?
a) 3800°C
b) 3900°C
c) 4000°C
d) 4100°C
Answer
Answer: b [Reason:] Carbon is used in carbon arc welding, at the negative terminal of the cathode and the metal which is being worked upon functions as the positive terminal. The temperature of the electrode at the positive terminal is 3900°C.
6. What is the temperature of the negative electrode in metal arc welding?
a) 2200°C
b) 2300°C
c) 2400°C
d) 2500°C
Answer
Answer: c [Reason:] In metal arc welding, the temperature of negative electrode is higher than the temperature of positive electrode. The temperature produced in a negative electrode of a metal arc weld is about 2400°C.
7. What is the temperature of the positive electrode in metal arc welding?
a) 2300°C
b) 2400°C
c) 2500°C
d) 2600°C
Answer
Answer: d
8. Which bead character is seen due to too high welding current?
a) Pilling of metal
b) Pilling of weld metal
c) Excess splatter
d) Small bead formation
Answer
Answer: c [Reason:] On provision of too low current, there is pilling of metal seen. When the voltage provided is very high, beads formed are too high. When the speed of weld is less, pilling of weld metal takes place and when welding currents are too high, excessive splatter formation occurs.
9. A smooth and regular bead cannot be formed in metal arc welding.
a) True
b) False
Answer
Answer: b [Reason:] Before the welding starts, the machine has to be adjusted very correctly. The current to be supplied and the voltage to be applied should not to be too low or high, and the welding speed should be normal. By doing this, regular and smooth beads will be formed.
10. Carbon is intended to be mixed in small amounts in the weld, in carbon arc welding.
a) True
b) False
Answer
Answer: b [Reason:] In carbon arc welding, the carbon is present at the negative electrode, where the electrode temperature is at 3200°C. This temperature is lesser than that at the positive electrode. Carbon electrode is kept at a lower temperature on the negative electrode, to avoid the mixing of carbon in the weld. If the carbon gets mixed with the weld, the weld might end up becoming brittle.
Set 4
1. Which of the following grinding wheel specified in ISO designation will represent Vitrified bond?
a) Z 46 K 5 E 17
b) C 600 K 5 B 17
c) C 8 K 5 R 17
d) A 80 K 5 V 17
Answer
Answer: d [Reason:] Fifth place of ISO designation of grinding wheel represents type of bond and “V” represents Vitrified bond type.
2. Grinding wheel specified as “C 8 K 5 R 17” in ISO designation. What is the type of bond present in grinding wheel?
a) Vitrified
b) Rubber
c) Shellac
d) Epoxy
Answer
Answer: b [Reason:] Fifth place of ISO designation of grinding wheel represents type of bond and “R” represents rubber.
3. Which of the following grinding wheel specified in ISO designation will represent Resin bond?
a) Z 46 K 5 E 17
b) C 600 K 5 B 17
c) C 8 K 5 R 17
d) A 80 K 5 V 17
Answer
Answer: b [Reason:] Fifth place of ISO designation of grinding wheel represents type of bond and “B” represents resin bond.
4. Which of the following grinding wheel specified in ISO designation will represent Shellac bond?
a) Z 46 K 5 E 17
b) C 600 K 5 B 17
c) C 8 K 5 R 17
d) A 80 K 5 V 17
Answer
Answer: a [Reason:] Fifth place of ISO designation of grinding wheel represents type of bond and “E” represents shellac.
5. Grinding wheel specified as “A 8 K 5 P 17” in ISO designation. What is the type of bond present in grinding wheel?
a) Vitrified
b) Rubber
c) Shellac
d) Epoxy
Answer
Answer: d [Reason:] Fifth place of ISO designation of grinding wheel represents type of bond and “P” represents rubber.
6. Which of the following will not have open structure?
a) A 46 K 5 B 17
b) C 600 K 8 B 17
c) C 8 K 5 9 17
d) A 80 K 10 B 17
Answer
Answer: a [Reason:] Fourth place of ISO designation of grinding wheel represents Structure and “5” comes under dense structure.
7. Which of the following has open structure?
a) A 46 K 5 B 17
b) C 600 K 8 B 17
c) C 8 K 5 3 17
d) A 80 K 4 B 17
Answer
Answer: b [Reason:] Fourth place of ISO designation of grinding wheel represents Structure and “8” comes under open structure.
8. A grinding wheel is specified as “C 10 K 8 R 17”. Which of the following is correct about this grinding wheel?
a) Very fine grains
b) Open structure
c) Aluminum oxide abrasive
d) Coarse grain
Answer
Answer: b [Reason:] Fourth place of ISO designation of grinding wheel represents Structure and “8” comes under open structure.
9. A grinding wheel is specified as “A 5 K 5 R 17”. Which of the following is correct about this grinding wheel?
a) Very fine grains
b) Open structure
c) Aluminum oxide abrasive
d) Coarse grain
Answer
Answer: c [Reason:] First place of ISO designation of grinding wheel represents grain type and “A” represents aluminum oxide.
10. A grinding wheel is specified as “C 5 K 5 R 17”. Which of the following is correct about this grinding wheel?
a) Very fine grains
b) Open structure
c) Rubber bond
d) Coarse grain
Answer
Answer: c [Reason:] Fifth place of ISO designation of grinding wheel represents type of bond and “R” represents rubber.
11. A grinding wheel is specified as “A 8 K 5 P 17”. Which of the following is correct about this grinding wheel?
a) Very fine grains
b) Open structure
c) Rubber bond
d) Coarse grain
Answer
Answer: d [Reason:] ‘8’ represents grain size, which is coarse.
12. Friability of grinding wheel is associated to
a) Hardness
b) Fracture
c) Size
d) None of the mentioned
Answer
Answer: b [Reason:] Friability is the ability to fracture under pressure so that when cutting edge become dull, the grain breaks off and exposes new grains which are sharp.
13. With time, grinding wheel starts rubbing work piece instead of cutting, due to decrease in sharpness. This phenomenon is known as
a) Loading
b) Glazing
c) Dressing
d) Trueing
Answer
Answer: b [Reason:] Glazing occurs when grinding wheel starts rubbing work piece instead of cutting.
14. Loss in sharpness of grinding wheel due to presence of chips in gaps of grains is termed as
a) Loading
b) Glazing
c) Dressing
d) Trueing
Answer
Answer: a [Reason:] Loading decrease sharpness of grinding wheel, when foreign material comes in between free space of wheel.
Set 5
1. 1’s complement of 1011101 is
a) 0101110
b) 1001101
c) 0100010
d) 1100101
Answer
Answer: c
2. 2’s complement of 11001011 is
a) 01010111
b) 11010100
c) 00110101
d) 11100010
Answer
Answer: c
3. On subtracting (01010)2 from (11110)2 using 1’s complements, the output will be
a) 010010
b) 110100
c) 101011
d) 110011
Answer
Answer: d
4. On subtracting (010110)2 from (1011001)2 using 2’s complements, we get
a) 0111001
b) 1100101
c) 0110110
d) 0101100
Answer
Answer: d
5. On subtracting (001100)2 from (101001)2 using 2’s complements, we get
a) 1101100
b) 011101
c) 11010101
d) 11010111
Answer
Answer: b
6. On addition of 28 and 18 using 2’s complements, we get
a) 00101110
b) 0101110
c) 00101111
d) 1001111
Answer
Answer: b
7. On addition +38 and -20 using 2’s complements, we get
a) 11110001
b) 100001110
c) 00001110
d) 110101011
Answer
Answer: c
8. On addition -46 and +28 using 2’s complements, we get
a) 11101100
b) 00010101
c) 101011111
d) 000100101
Answer
Answer: a
9. The addition of -33 and -40 using 2’s complements is equal to
a) 01001110
b) 111010101
c) 10110001
d) 10110001
Answer
Answer: d
10. On subtracting +28 and +29 using 2’s complements, we get
a) 11111010
b) 111111001
c) 010101011
d) 00000101
Answer
Answer: d