George has four samples of substances:
sample a: 5 kg of iron
sample b: 2 kg of copper
sample c: 2 kg of iron
sample d: 5 kg of nickel
which of the following samples have the same melting point?
sample a and sample c
sample b and sample c
sample a and sample b
0 sample a and sample d

The answer to your question is sample A and sample C.

Explanation:

Melting point is a physical property of substances, physical properties do not depend on the amount of matter, so it doesn't matter that in one sample we have 5 kg and in the other we have 2 kg.

Besides in samples B and C we have the same amount of matter, they are different substances(copper and iron) so, their melting points are different.

Also, in samples A and D, we have the same amount of matter, but they are different substances so their melting points are different.