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.
Answer: heck the chemistry app itll help you i dont know this answer but the app will tell u!
Ca.
Hydrogen and Carbon combined
Zn = zinc which is a metal, not a carbon atom
Cl=chlorine, just not a carbon atom
Sn isn’t a carbon atom.
I Am positive that it is Ca because Ca means carbon
If I remember correctly from my science class, it is Protons and Neutrons.
Hope this helps, if not, comment below please!!!