Which of these methods could are used to separate an insoluble solid and soluble solid

An excess of lithium oxide undergoes a synthesis reaction with water to produce lithium hydroxide li2o+h2o→2lioh if 1.05 g of water reacted, what is the theoretical yield of lithium hydroxide? a) 5.83 x 10–2 g lioh b) 1.17 x 10–1 g lioh c) 2.79 x 100 g lioh d) 1.40 x 100 g lioh

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

What is the subscript for oxygen in its molecular formula