When 10 grams of reactant A reacts with 20 grams of reactant B, only 15 grams of product C is produced. What is the percentage yield of this reaction?

A. 50%

B. 75%

C. 100%

D. 150%

Which of the following statements best describes a limiting reactant?

A. The reactant that is completely consumed in a reaction.

B. The reactant that is present in excess.

C. The reactant that determines the amount of product formed.

D. Both A and C.

In a balanced chemical equation, the number of atoms of each element on the reactant side is:

A. Greater than on the product side.

B. Lesser than on the product side.

C. Equal to the number on the product side.

D. Not related to the product side.

If the actual yield of a reaction is 80 grams and the theoretical yield is 100 grams, what is the percentage yield?

A. 60%

B. 70%

C. 80%

D. 90%

Which factor does NOT affect the percentage yield in real-world reactions?

A. Purity of reactants.

B. Temperature.

C. Catalysts.

D. Color of the reactants.

a) Define the concept of a limiting reactant and explain its significance in predicting product yields. [3]

b) Given the reaction: 2H₂ + O₂ → 2H₂O, if 4 moles of hydrogen gas react with 2 moles of oxygen gas, identify the limiting reactant and the number of moles of water produced. [3]

a) Describe the importance of balancing chemical equations in stoichiometric calculations. [3]

b) For the reaction: N₂ + 3H₂ → 2NH₃, if 28 grams of nitrogen gas reacts with an excess of hydrogen gas, calculate the mass of ammonia produced. (Given: Molar mass of N₂ = 28 g/mol, NH₃ = 17 g/mol) [3]

a) Define the term 'percentage yield' and explain factors that might affect it in real-world reactions. [4]

b) If a reaction has a theoretical yield of 50 grams, but only 40 grams of product is obtained, calculate the percentage yield. [2]

a) Define Avogadro's number and explain its significance in relating the macroscopic world to the atomic/molecular level. [3]

b) How many atoms are present in 2 moles of carbon? [2]

c) If you have 12 grams of carbon, how many moles of carbon atoms do you have? (Given: Molar mass of Carbon = 12 g/mol) [2]

a) Describe the difference between an element, a compound, and a mixture. [3]

b) Given a sample containing iron and sulphur, how would you determine if it's a mixture or a compound? [3]

c) Why is the mole concept crucial for stoichiometric calculations? [2]