Answer 1) Option D) 3 moles.
Explanation : In the reaction we can see that the number of moles of hydrogen are equal to the number of water molecules formed. Also, oxygen is found t o be the limiting reactant as equal number of moles are not produced in the reaction.
Here when we use 3 moles of hydrogen then 3 moles of water will be produced. As we are ignoring the moles of oxygen here as that is a limiting reactant.
Answer 2) Option A) 9 moles of reactants chemically change in to 11 moles of product.
Explanation : We can see that 1 mole of pentane reacts with 8 moles of oxygen to produce 5 moles of carbon dioxide and 6 moles of water. So when we add the reactants side we get 1 + 8 = 9 moles and in products it has 5 + 6 = 11 moles.
Hence, 9 moles of reactants produce 11 moles of products.
Answer 3) Option A) 0.62 moles.
Explanation : Here, the number of moles of Cu reacts with 2 moles of silver nitrate and gives 1 mole of copper nitrate and 2 moles of silver.
So, the ratio is 1 : 2 in the reactants side, Now, when we have 1.23 moles of silver nitrate then to calculate the number of Cu.
we can simply cross multiply and get the answer as 1.23 / 2 = 0.615 = ~ 0.62 moles.