CWB Level 3 Module 20 Exam Questions And
Accurate Answers (A+)
Compared to non metals, metals have - Answer 1. High electrical conductivity
2. High thermal conductivity
3. High specific gravity
4. often ductile and can be formed
5. metal's physical properties can be greatly influenced by it's alloying materials.
In metals, electrical and thermal conductivity. - Answer Paralell each other
Cu and Al are used as. - Answer electrical conductors
Gold and silver are used as. - Answer electrical contacts
Electrical conductivity helps for. - Answer arc welding and resistance welding
Very high thermal conductivity makes. - Answer arc welding difficult and resistance
welding impossible bcz heat is rapidly removed from weld
Thermal conductivity of Cu - Answer 394 W(m c) / 230 BTU
Electrical resistivity of Cu - Answer 1.72 x 10 ^ -8 ohm m
Thermal conductivity of Aluminum - Answer 222 W(m c) /130 BTU
, Electrical resistivity of Al - Answer 2.83 x 10 ^ -8 ohm m
Thermal conductivity of Carbon steel - Answer 46 W(m c) /26.8 BTU
Electrical resistivity of Carbon steel - Answer 16.0 x 10 ^ -8 ohm m
Pure Cu - Answer Cannot be seam / spot/ projection welded
Al - Answer Cannot be spot / seam welded in thin sections. High currents required
Carbon steel. - Answer Easily welded by all resistance welding methods
Two ores of iron - Answer Magnetite (Fe3 O4) & Hematite ( Fe2O3)
Ore of Al - Answer Bauxite ( Al2 O3)
Iron is extracted by - Answer smelting in a blast furnace by blowing hot air over coke to
produce carbon monoxide, which removes O2 from the ore, leaving the iron as a liquid
metal.
Al from Bauxite cannot be extracted by. - Answer heating method
Bauxite is extracted by. - Answer electrical method
Plot of free energy of oxides - Answer Ellingham diagram
Large free energy indicates a - Answer very stable oxide
Accurate Answers (A+)
Compared to non metals, metals have - Answer 1. High electrical conductivity
2. High thermal conductivity
3. High specific gravity
4. often ductile and can be formed
5. metal's physical properties can be greatly influenced by it's alloying materials.
In metals, electrical and thermal conductivity. - Answer Paralell each other
Cu and Al are used as. - Answer electrical conductors
Gold and silver are used as. - Answer electrical contacts
Electrical conductivity helps for. - Answer arc welding and resistance welding
Very high thermal conductivity makes. - Answer arc welding difficult and resistance
welding impossible bcz heat is rapidly removed from weld
Thermal conductivity of Cu - Answer 394 W(m c) / 230 BTU
Electrical resistivity of Cu - Answer 1.72 x 10 ^ -8 ohm m
Thermal conductivity of Aluminum - Answer 222 W(m c) /130 BTU
, Electrical resistivity of Al - Answer 2.83 x 10 ^ -8 ohm m
Thermal conductivity of Carbon steel - Answer 46 W(m c) /26.8 BTU
Electrical resistivity of Carbon steel - Answer 16.0 x 10 ^ -8 ohm m
Pure Cu - Answer Cannot be seam / spot/ projection welded
Al - Answer Cannot be spot / seam welded in thin sections. High currents required
Carbon steel. - Answer Easily welded by all resistance welding methods
Two ores of iron - Answer Magnetite (Fe3 O4) & Hematite ( Fe2O3)
Ore of Al - Answer Bauxite ( Al2 O3)
Iron is extracted by - Answer smelting in a blast furnace by blowing hot air over coke to
produce carbon monoxide, which removes O2 from the ore, leaving the iron as a liquid
metal.
Al from Bauxite cannot be extracted by. - Answer heating method
Bauxite is extracted by. - Answer electrical method
Plot of free energy of oxides - Answer Ellingham diagram
Large free energy indicates a - Answer very stable oxide
