Note: See PART 2 for a better question.
1 kg of matter has infinite number of parts. Infinite number of things together can make an infinite amount of matter. 1 kg is not equal to infinite amount. We face an illogical result.
Note I: The terms 'infinite divisibility' and 'infinitesimal' MAY be related.
In logical explanations, what is the mistake in this argument?
Does 1/2+1/4+1/8+1/16+... get over 1? First, we may (wrongly) think that the answer is 'Yes', but actually the answer is 'No'.
A more interesting form of this problem: An amount starts from 0, and increase by every moment. Does it eventually get over 5?
This is the best example of possible mistake of intuition that I faced (I have not examined all examples), and I call it a paradox:
For a long time, the idea that such a potentially infinite summation could produce a finite result was considered paradoxical. - Series (mathematics), Wikipedia
Note II: 'Zeno's paradoxes' and 'Convergent series' may be related.
A possible answer?
I think the answer to both questions may be that 'there is an infinite number of numbers or measurements between 0 and a finite number'.