D. Give reasons for each of the following.
1. Aluminium foils are used to wrap food items.
2.Sodium and potassium are stored in kerosene.
3.Silver cannot displace copper from its salt solutions.
4. Electric wires are made of copper.
5.Copper items become green with the passage of time.
Answers
Answer:
1 because it can preserve the food from light O2 and moisture.
2 because they are highly reactive and can even react with air.(oil is alkali so hence used to store these items)
3 because silver is less reactive then copper.
4 because copper is cheap and great conductor if electricity.
5 Copper turns green because of chemical reactions with the elements. ... Just as iron that is left unprotected in open air will corrode and form rust.
Answer:
1. Aluminium foil is used to wrap food items bcoz it can be easily beaten into thin sheets and also it is a very good conductor of heat.
2. Sodium and potassium are stored in kerosene bcoz when they are exposed to open environment they react vigorously and catch fire.
3. Silver is a more noble metal than copper. Also the reduction potential of silver is higher than the reduction potential of copper. That's why silver cannot displace copper from its salt solution.
4. Copper is good conductor of electricity and it can be easily drawn into wires. That's why wires are made up of copper.
5. Copper items become green with the passage of time bcoz copper reacts with surrounding moisture or oxygen and forms a light green coloured layer called patina.
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