It would be Atom 2 because the proton and neutron are both nine and the election is 8 which is -1 to nine <span />
Answer:
The answer to your question is letter D. 2.02 g
Explanation:
Data
moles of Ne = 0.100
atomic mass of Neon = 20.18 g
Process
1.- Use proportions to find the answer
20.18 g of Ne ------------------ 1 mol of Ne
x ------------------ 0.1 moles
x = (0.1 x 20.18)/1
x = 2.018
2.- Consider the significant figures
0.100 has three significant figures so the answer must be 2.02 g
Cs -137 has a half life of about 30 years. If 60 years pass, there is two half lives passed so 1/2 * 1/2= 1/4. Take 1/4 and multiply it with the mass given:
(1/4)*20mg=5mg left
