Question 1:

What is a molar ratio in stoichiometry?

Explanation: A molar ratio in stoichiometry refers to option A, which is the ratio of coefficients between reactants and products in a balanced chemical equation.

Question 2:

In the reaction 2H2 + O2 → 2H2O, what is the molar ratio of hydrogen (H2) to water (H2O)?

Explanation: The molar ratio of hydrogen (H2) to water (H2O) in the given reaction is 2:2 or simply 1:1, option C.

Question 3:

How many grams of oxygen (O2) are required to react completely with 5 moles of methane (CH4) according to the equation CH4 + 2O2 → CO2 + 2H2O?

Explanation: According to the balanced chemical equation, the molar ratio of methane (CH4) to oxygen (O2) is 1:2. Therefore, 5 moles of methane (CH4) will require 2 * 5 = 10 moles of oxygen (O2). To convert moles to grams, we multiply by the molar mass of oxygen (32 g/mol). The result is 320 grams, which is option A.

Question 4:

In the reaction 2NaOH + H2SO4 → Na2SO4 + 2H2O, how many grams of sodium sulfate (Na2SO4) are produced when 100 grams of sodium hydroxide (NaOH) react?

Explanation: The molar ratio of sodium hydroxide (NaOH) to sodium sulfate (Na2SO4) in the given reaction is 2:1. To determine the number of moles of sodium sulfate produced, we need to convert the mass of sodium hydroxide to moles, then use the molar ratio to find the moles of sodium sulfate, and finally convert back to grams using the molar mass of sodium sulfate (142 g/mol). The result is 100 * (1/40) * (1/2) * 142 = 142 grams, which is option A.

Question 5:

In the reaction 2Mg + O2 → 2MgO, how many moles of magnesium oxide (MgO) are produced from 4 moles of magnesium (Mg)?

Explanation: According to the balanced chemical equation, the molar ratio of magnesium (Mg) to magnesium oxide (MgO) is 2:2 or simply 1:1. Therefore, 4 moles of magnesium (Mg) will produce 4 moles of magnesium oxide (MgO), option A.