Answer:
1870 dalton simple sphere
1897 plum pudding positive mass........
1905 Rutherford electrons orbitting....
1913 Bohr electrons in shells......
it remains unchanged
Fission and fusion process
C
Explanation:
m₂ = 1.212 kg
m₁a₁ = F = m₂a₂
1.515(12) = m₂(15)