Answer:
Magnetic property
Explanation:
Iron filling is a magnetic compound, unlike the salt crystals. This means they are attracted by magnets.
To separate a mixture of iron filling s and salt crystals, a magnet should be used to remove the iron fillings from the mixture.
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False weight is dependent on the force of gravity
The much of the sample that would remain unchanged after 140 seconds is 2.813 g
Explanation
Half life is time taken for the quantity to reduce to half its original value.
if the half life for Scandium is 35 sec, then the number of half life in 140 seconds
=140 sec/ 35 s = 4 half life
Therefore 45 g after first half life = 45 x1/2 =22.5 g
22.5 g after second half life = 22.5 x 1/2 =11.25 g
11.25 g after third half life = 11.25 x 1/2 = 5.625 g
5.625 after fourth half life = 5.625 x 1/2 = 2.813
therefore 2.813 g of Scandium 47 remains unchanged.
This is a physical change.
