Question 1: Define hydrogen and state its chemical symbol.

Answer: Hydrogen is a colorless, odorless, flammable gas with the chemical symbol H.

Question 2: Describe the mechanism of how hydrogen reacts with oxygen to produce water.

Answer: Hydrogen reacts with oxygen in a combustion reaction, where two H₂ molecules combine with one O₂ molecule to form two H₂O molecules, releasing energy.

Question 1: Calculate the molar volume of 2 grams of hydrogen gas at standard temperature and pressure (STP). (Molar mass of H₂ = 2 g/mol, Molar volume at STP = 22.4 L/mol)

Answer: 22.4 liters

Question 2: If 3 liters of hydrogen gas are collected at STP, how many moles of hydrogen are present?

Answer: 0.134 mol

Question 1: Describe the procedure to test for hydrogen gas in a laboratory setting.

Answer: Hydrogen gas can be tested by bringing a lit splint to the mouth of the test tube; a squeaky pop sound indicates the presence of hydrogen.

Question 2: List two safety precautions to follow when working with hydrogen gas.

Answer: Ensure proper ventilation and avoid open flames or sparks near hydrogen gas.

Question 1: A scientist collects 5 liters of hydrogen gas at room temperature and pressure. The gas is then reacted with oxygen to produce water. How many grams of water are formed? (Use molar volume = 22.4 L/mol, molar mass of H₂O = 18 g/mol)

Answer: 11.25 grams

Question 1: Explain why hydrogen is considered a clean fuel and mention one industrial application.

Answer: Hydrogen is considered a clean fuel because it produces only water when burned, releasing no carbon emissions. It is used in fuel cells to generate electricity for vehicles and power plants.

Question 2: Identify the main safety concern when storing large quantities of hydrogen and suggest a safety measure.

Answer: Hydrogen is highly flammable and explosive; storing it in well-ventilated areas and using proper containers reduces the risk.