Solder is an alloy of
- A.Cu and Sn.
- B.Fe and Zn.
- C.Pb and Sn.
- D.Ag and Zn.
Correct answer
Explanation
The correct answer is C, Pb and Sn. Traditional solder is an alloy of lead and tin, often in a ratio of about 60 parts tin to 40 parts lead.
Solder is used to join metal parts, especially wires and components in electrical circuits. Its key property is a low melting point, lower than that of either pure lead (327 °C) or pure tin (232 °C); the mixture of about 63 per cent tin and 37 per cent lead melts at only about 183 °C. This lets it melt easily under a soldering iron without damaging the parts being joined, and then set into a firm, conducting joint. Because lead is toxic, many countries now use lead-free solders made mainly of tin with small amounts of silver and copper.
A is wrong: copper and tin together make bronze.
B is wrong: iron coated with zinc is galvanised iron; this is a coating, not solder.
D is wrong: silver and zinc do not form solder; brass, a similar alloy, is copper and zinc.
Exam tip: solder, lead and tin; bronze, copper and tin; brass, copper and zinc.
Practice Questions
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- C.ADP
- D.Pyruvic acid
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- B.Mg < Al < Zn < Fe
- C.Mg > Zn > Fe > Al
- D.Fe > Mg > Al > Zn
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- A.Anaemia
- B.Scurvy
- C.Rickets
- D.Cholera
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- A.1 and 2 only
- B.1 only
- C.2 and 3 only
- D.1, 2 and 3
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- A.sulphuric acid
- B.bleaching powder
- C.caustic soda
- D.nitric acid
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