You are using the internet right now. The question told you not to. Lol
the mass of a carbon atom is 1.994 x 10⁻²³ g
the mass of the carbon sample is 12.01 g
to find the number of Carbon atoms we have to divide the mass of sample by mass of a carbon atom.
number of C atoms =

therefore number of atoms = 6.023 X 10²³ atoms of carbon
Scandium (Sc) has the largest atomic mass.
Answer: Sc (Scandium)
Time taken for star to reach Earth = 7.5 years
<h3>Further explanation</h3>
Given
7.5 light years(distance Earth-star)
Required
Time taken
Solution
Speed of light=v = 3 x 10⁸ m/s
1 light years = 9.461 × 10¹⁵ m= distance(d)
So time taken for 1 light years :
time(t) = distance(d) : speed(v)
t = 9.461 × 10¹⁵ m : 3 x 10⁸ m/s
t = 3.154 x 10⁷ s = 1 years
So for 7.5 light years, time taken = 7.5 years
A. 1,5,3,4
the 3 and 4 increase the number of oxygens on the right side to 10 so you have to put a 5 in front of the oxygen of the left side to balance it out