Food Packaging Technology Multiple Choice Questions & Answers (MCQs) on “Manufacture of Tinplate – 1”.
1. The thickness of a tinplate sheet is around ______
a) 0.5–1.5 mm
b) 0.15–0.5 cm
c) 0.5–1.5 cm
d) 0.15–0.5 mm
Answer: d
Clarification: The term tinplate refers to low-carbon, mild steel sheet varying in thickness from around 0.15–0.5 mm with a coating of tin between 2.8 and 17 gsm (g m−2) (0.4–2.5 μm thick) on each surface of the material.
2. Tinplate is a combination of tin and steel.
a) True
b) False
Answer: a
Clarification: The given statement is true. The combination of tin and steel imparts properties – good strength with excellent fabrication qualities like ductility and drawability, weldability, lubricity, lacquerability, non-toxicity and provides corrosion-resistance. Tin and steel together can undergo extensive deformation without fracture.
3. The temperature at which iron ore is heated is around ______
a) 2500°C
b) 1000°C
c) 1200°C
d) 1800°C
Answer: d
Clarification: The iron ores used are generally hematite (Fe2O3) with some magnetite (Fe3O4). Commercial extraction of iron from its ores is carried out in blast furnaces, where a mixture of iron ores, solid fuel (coke) and fluxes (limestone and dolomite) are heated to around 1800°C. This results in the reduction of most of the iron oxides to metallic iron (m.p. ≈ 1200°C). Today, modern blast furnaces are capable of producing molten iron of near constant composition at high rates.
4. In tinplate, steel serves as the base material.
a) True
b) False
Answer: a
Clarification: The given statement is true. In tinplate, steel serves as the base material. The tin coating adheres sufficiently to the steel base so that it will withstand any degree of deformation that the steel is able to withstand without flaking.
5. The melting point of metallic ores is around ______
a) 1000°C
b) 1200°C
c) 1800°C
d) 800°C
Answer: b
Clarification: The melting point of metallic ores is around 1200°C. Iron ores are generally heated at 1800°C, so that it reduces to metallic ores.
6. Pig iron from blast furnace contains ________ carbon.
a) 1.5%–2.0%
b) 2.5%–6.0%
c) 6.5%–8.0%
d) 3.5%–5.0%
Answer: d
Clarification: The pig iron from a blast furnace contains 3.5%–5.0% carbon. Carbon is the most important alloying element for steel and affects the strength of cans. Carbon in higher concentration, when combined with manganese results in higher steel strength.
7. Pig iron from blast furnace contains ________ silicon.
a) 2.5%–3.0%
b) 0.3%–1.0%
c) 1.5%–2.0%
d) 0.1%–0.5%
Answer: b
Clarification: Pig iron from blast furnace contains 0.3%–1.0% silicon. Hardness of pig iron decreases with increase in silicon. But, addition of a little amount of silicon improves the microstructure.
8. Pig iron from blast furnace contains ________ manganese.
a) 5%
b) 10%
c) 1%
d) 2.5%
Answer: d
Clarification: Pig iron from blast furnace contains up to 2.5% manganese. Manganese greatly contributes to increasing the hardness of the pig iron.
9. Pig iron from blast furnace contains ________ phosphorous.
a) 0.5%
b) 1%
c) 5%
d) 3%