Alloys like manganin, eureka, constantan etc. are used in making standard resistance coils. Why?

Invar is used for making pendulum of clocks. Why?

Copper containers are not used to make or keep food containing acid. Why?

Which of the following material is used to make wire wound standard resistors?

Constantan wire is used for making standard resistance, because it has......(a)High melting point (b)Low specific resistance (c)High specific resistance (d)Negligible temperature coefficient of resistance

Which alloy steel is used for making permanent magnets?

Some alloys are given below. Alnico, stainless steel, Nichrome a) Which alloy is used for making heating coll? b) Which alloy is used for making permanent magnent? c) What is the similarity between stainless steel and nichrome?