Ignoring the n's, there would only be one unpaired electron.
The answer is rubidium -91 because it takes a shorter time of 58.4 seconds to become stable.
First, calculate the amount fo Na2O that should be produced with the given amount of sodium using proper dimensional analysis and the balanced chemical reaction,
theoretical amount of Na2O = (54.1 g of Na)(1 mol Na/23 g Na)(2 mos Na2O/4 mols Na)(62 g Na2O/ 1mol Na2O)
theoretical amount of Na2O = 72.9 g of Na2O
Calculation of percent yield,
% yield = (61.8 g Na2O) / (72.9 g of Na2O) x 100%
% yield = 84.75%
Answer: 84.75%