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Asked in GUJCET 2019 · Dia, para and ferromagnetism
Idea: the name is the mnemonic. AL-NI-CO stands for aluminium, nickel and cobalt, alloyed with iron and usually a little copper.
So the list must contain Al, Ni and Co.
Only one option does: Al, Ni, Cu, Co.
Alnico is a hard magnetic material -- a broad hysteresis loop, high retentivity and high coercivity -- which is why it is used for permanent magnets and loudspeaker magnets rather than for transformer or electromagnet cores.
So Alnico is an alloy of Al, Ni, Cu and Co.
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