Answer: hello your question has some missing details attached below is the missing details
answer : 25.5% Â ( B )
Explanation:
Determine percentage yield
molar mass = 35 g/mol
mass of Li₃N(s) = 70 g
product  LiH(s) = 8.0 g ( actual yield )
theoretical yield ( LiH ) = Â 4 * 7.95 Â = 31.8 g
percentage yield = actual yield * 100 / theoretical yield
              = 8 * 100/31.8
              = 25.5%