Description : In arc welding, Argon is used because of its - (1) Low reactivity with metal (2) Ability to lower the melting point of the metal (3) High flammability (4) High calorific value
Last Answer : (1) Low reactivity with metal Explanation: In arc welding, Argon is used as a shielding gas because it is chemically inert and forms no compounds. At the high temperatures that welding requires, the ... to brittle welds and instability in the welding arc. So,argon and other inert gases are sprayed.
Description : Argon is used in arc welding because
Last Answer : Argon is used in arc welding because A. low reactivity with metal B. ability to lower the ... of metal C. flammability D. high calorific value
Description : A metallic alloy in general as compared to their pure metal components is (A) More corrosion resistant (B) Having higher melting point (C) Having lower hardness, reactivity and fusibility (D) Having lower electrical conductivity
Last Answer : (A) More corrosion resistant
Description : Unsaturated oils compared to saturated oils have (A) Lower melting point & higher reactivity to oxygen (B) Higher melting point & higher reactivity to oxygen (C) Lower melting point & lower reactivity to oxygen (D) Higher melting point & lower reactivity to oxygen
Last Answer : (A) Lower melting point & higher reactivity to oxygen
Description : Fats as compared to oils have (A) More unsaturated glycerides of fatty acids (B) Less unsaturated glycerides of fatty acids (C) Much higher reactivity to oxygen (D) Lower melting point
Last Answer : (B) Less unsaturated glycerides of fatty acids
Description : Cold cracking in the heat affected zone of a high strength steel weld can take place because of the (A) Retained austenite (B) Martensite formation (C) Relatively high sulphur content in the base metal (D) Sufficient hydrogen present in the welding arc
Last Answer : (B) Martensite formation
Description : Refractory metals are known for which of the following properties: w) lack of chemical reactivity x) low density y) high melting point z) high thermal conductivity
Last Answer : ANSWER: Y -- HIGH MELTING POINT
Description : Why do noble gases such neon or argon have very low chemical reactivity?
Last Answer : They have very low chemical reactivity because they all have afull outer shell, i.e. they all have 8 electrons in their outershell. This makes them very stable and thus not very reactive.
Description : Helium (He), neon (Ne) and argon (Ar) are all colorless, odorless gases with low chemical reactivity. Based on the periodic table, which other element would also have those same properties?
Last Answer : Helium
Description : Why is melting wax a physical properties of flammability is a chemical property?
Last Answer : Melting is a physical property because the chemical composition remain unchanged.Flammability is a chemical property because involve a combustion reaction.
Description : What is the melting point of argon ?
Last Answer : Argon melting point - 189 degrees Celsius.
Description : Which noble gas has the highest melting point ? w) argon x) krypton y) xenon z) radon
Last Answer : ANSWER: Z -- RADON
Description : Explain the shielded metal arc welding (SMAW) processes with neat sketch. State its two advantages and disadvantages.
Last Answer : Working : Shielded metal arc welding uses a metallic consumable electrode of a proper composition for generating arc between itself and the parent work piece. The molten electrode metal fills the weld ... . 2. Weld may contain slag inclusions 3. Fumes make difficult the process control.
Description : Draw a schematic of a set up of shielded metal arc welding.
Last Answer : Fig. Shielded metal arc welding set-up
Description : Coke oven gas produced by high temperature carbonisation of coal (as compared to that produced by low temperature carbonisation), has (A) Higher calorific value (B) Lower hydrogen content (C) Both (A) and (B) (D) Neither (A) nor (B)
Last Answer : (D) Neither (A) nor (B)
Description : In high temperature carbonisation of coal compared to low temperature carbonisation (A) Yield of ammonia is less (B) Aromatic content of tar is low (C) H2 content in the coke oven gas is more (D) Calorific value of the coke oven gas is lower
Last Answer : (C) H2 content in the coke oven gas is more
Description : The catalytic activity of transition metals and their compounds is ascribed mainly to (1) their chemical reactivity (2) their magnetic behaviour (3) their unfilled d-orbitals (4) their ability to adopt variable oxidation states
Last Answer : (4) their ability to adopt variable oxidation states
Description : Diamond has each of the following properties except: w) extreme hardness x) ability to conduct electricity y) high melting point z) tendency to burn in air
Last Answer : ANSWER: X -- ABILITY TO CONDUCT ELECTRICITY
Description : Tar is a better fuel than furnace oil, because of its (A) Higher calorific value (B) Lower sulphur content (C) Higher emissivity (0.8-0.9) resulting in higher radiation heat transfer rate (D) Both (A) and (B)
Last Answer : (D) Both (A) and (B)
Description : __________ prohibits the use of alcohols directly in petrol engines. (A) Low octane number (B) High cost & availability (C) Low flash point (D) Low calorific value
Last Answer : (B) High cost & availability
Description : For photoelectric effect to take place, the metal used as the cathode should have – (1) high melting point (2) low melting point (3) low work function (4) low resistance
Last Answer : (3) low work function Explanation: The photoelectric effect is the propensity of high-energy electromagnetic radiation to eject electrons from a given material. The photoelectric effect has been utilized in devices called photocells, consisting of two electrodes in a sealed vacuum tube.
Description : For photoelectric effect to take place, the metal used as the cathode should have______ (1) high melting point (2) low melting point (3) low work function (4) low resistance
Last Answer : low work function
Description : Highly reactive coke have lower (A) Porosity (B) Coke reactivity index (CRI) (C) Critical air blast (CAB) value (D) Both (B) and (C)
Last Answer : (C) Critical air blast (CAB) value
Description : If Metal A displaces Metal B from its solution, then Metal A _______. (1) is more reactive than B (2) is less reactive than B (3) is heavier than B (4) has the same reactivity as B
Last Answer : (1) is more reactive than B
Description : Coke oven gas is a better fuel than blast furnace gas, because of its higher (A) Calorific value, cleanliness and relatively low distribution cost (due to its low specific gravity) (B) Adiabatic flame temperature ... release rate (thus requiring smaller combustion chamber) (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : What type of arc welding equipment is necessary when participating in arc welding?
Last Answer : The most important equipment you can have is your safety equipment, your gloves, visor and heavy-duty clothing. You have to have some sort of a power source to generate the electricity necessary for arc welding, so I'd say a power source is your most important arc welding equipment.
Description : The required DC voltage for arc welding is- (1) 6 to 9 V (2) 50 to 60 V (3) 200 to 250 V (4) 90 to 100 V
Last Answer : (3) 200 to 250 V
Description : Projection welding is (i) Electric arc welding (ii) Gas welding (iii)Spot welding (iv) None
Last Answer : (iv) None
Description : Which type of welding is generally used in automobile sector? a) Electric arc welding b) Electric resistance welding c) Gas welding d) Forge welding
Last Answer : b) Electric resistance welding
Description : Among gas and electric arc welding, which has the higher rate of heating? a) Gas welding b) Electric arc welding c) Gas welding and electric arc welding have equal rate of heating d) Cannot be determined
Last Answer : b) Electric arc welding
Description : Rails in the field are generally welded by using a) Thermit welding b) Gas welding c) Electric arc welding d) Forge welding
Last Answer : a) Thermit welding
Description : The electric arc welding is a type of ............. welding. (a) forge (b) fusion
Last Answer : b) fusion
Description : Thermit welding is categorised as the __________ welding. (A) Forge (B) Fusion (C) Resistance (D) Arc
Last Answer : (B) Fusion
Description : Consumable electrodes are used in the __________ welding. (A) Gas (B) Arc (C) Thermit (D) Resistance
Last Answer : (B) Arc
Description : Projection welding & stud welding is categorised as the __________ welding. (A) Pressure (B) Thermit (C) Resistance (D) Arc
Last Answer : C) Resistance
Description : Which of the following mainly decides the current to be employed is arc welding? (A) Electrode size (B) Plate thickness (C) Voltage across the arc (D) Welded portion length
Last Answer : (A) Electrode size
Description : Coating provided on the electrodes used in the arc welding is not expected to (A) Add alloying elements (B) Prevent electrode from contamination (C) Stabilise the arc (D) Provide protective atmosphere to weld
Last Answer : (B) Prevent electrode from contamination
Description : Stainless steel is welded using (A) Oxy-acetylene flame (B) Oxy-hydrogen flame (C) Arc welding (D) Inert gas arc welding
Last Answer : (D) Inert gas arc welding
Description : When MMA welding what will be the effect on the weld f the power source was changed from AC to DC-ve? a) None b) Higher deposition rate c) It would slightly increase the depth of penetration d) The arc would become unstable
Last Answer : b) Higher deposition rate
Description : What is a typical ARC voltage setting when welding with the TIG (GTAW) process? a) 18-20V b) 24-26V c) 10-12V d) 70-90V
Last Answer : c) 10-12V
Description : A butt weld has been made by MMA in a 50mm thick impact tested steel plate. The welding electrode used was a basic type, 5mm diameter. The measured welding parameters for one of the runs was 250 amps, 24 volts, using DC ... given to calculate the arc energy b) 1.9 kJ/mm c) 1.87 kJ/mm d) 2.0 kJ/mm
Last Answer : d) 2.0 kJ/mm
Description : List common equipments used for arc welding process.
Last Answer : 1. A.C. or D.C. machine 2. Electrode (bare or coated) 3. Electrode Holder 4. Cables and its connectors 5. Chipping Hammer 6. Earthing Clamps 7. Wire-brush 8. Helmet 9. Safety Goggles 10. Hand Gloves 11. Apron Sleeves etc.
Description : Describe the working principle of Arc Welding.
Last Answer : Arc welding is the most extensively employed method of joining metal parts. Here the source of heat is an electric arc. The arc column is generated between an anode which is the positive pole of D.C. ... also melted and is transferred in to the metal in the form of globules of molten metal.
Description : Compare resistance welding and arc welding.
Last Answer : Sr. No Resistance Welding Arc Welding 1 It is plastic welding It is fusion welding. 2 Arc is produced by heat due to resistance of flow of current by work and by application ... 8 Less skilled operator can do the job. More skilled operator is required to the job
Description : Compare between Resistance welding and Arc welding on any six points.
Last Answer : Sr.No Parameters Resistance Welding Arc Welding 1 Type of welding Plastic/Pressure/Non-fusion welding Fusion/Non pressure welding 2 Principle of heat developed Heat ... It is suitable for mass production It is suitable for heavy job, maintenance and repair work
Description : The commonly used gases in tungsten arc welding are 1.Hydrogen and oxygen 2.Hydrogen and organ 3.Hydrogen and helium 4.Helium and argon
Last Answer : The commonly used gases in tungsten arc welding are Helium and argon
Description : For arc welding current range is usually (1) 10 to 15 A (2) 30 to 40 A (3) 50 to 100 A (4) 100 to 350 A
Last Answer : For arc welding current range is usually 100 to 350 A
Description : Identify the correct combination of respective Electric arc welding and Electric resistance welding methods : (A) Butt welding and Seam welding (B) Hydrogen shielding and Projection welding (C) Seam welding and Coated electrode welding (D) Coated electrode welding and Hydrogen shielding
Last Answer : Identify the correct combination of respective Electric arc welding and Electric resistance welding methods : (A) Butt welding and Seam welding (B) Hydrogen shielding and Projection welding ... Seam welding and Coated electrode welding (D) Coated electrode welding and Hydrogen shielding
Description : The supply for arc welding is :
Last Answer : The supply for arc welding is : Low voltage, high current ac or dc voltage
Description : Arc welding uses following electric supply (A) ac (B) dc (C) both ac and dc (D) spiral waveform
Last Answer : both ac and dc