Question 1: Hydrogen is the simplest and most abundant element in the universe. It consists of one proton and one electron. In chemical tests, hydrogen gas can be distinguished by its reaction with a lit splint. Explain the principle behind how hydrogen gas is tested in the laboratory.

Answer: Hydrogen gas is tested by bringing a lit splint into the gas; if it burns with a pop sound, it indicates the presence of hydrogen due to its explosive reaction with oxygen.

Question 1: Describe two physical properties of hydrogen gas that make it useful in industry.

Answer: Hydrogen is a colorless, odorless, and highly flammable gas; it has a very low density, being the lightest gas.

Question 2: Which safety precautions should be taken when performing a hydrogen test in the laboratory?

Answer: Use a well-ventilated area, avoid open flames, and handle hydrogen with care due to its flammability and explosive potential.

Question 3: Multiple Choice: During a hydrogen test, a lit splint produces a 'pop' sound. What does this indicate? A) The presence of oxygen B) The presence of hydrogen C) The presence of carbon dioxide D) The presence of nitrogen

Answer: B

Question 1: Write the chemical equation for the combustion of hydrogen gas.

Answer: 2H₂ + O₂ → 2H₂O

Question 2: Fill in the blank: When hydrogen burns in oxygen, it produces ________ as the only product.

Answer: water

Question 1: Calculate the volume of hydrogen gas (in liters) at STP produced when 4 grams of sodium reacts with water, given that the reaction produces hydrogen gas according to: 2Na + 2H₂O → 2NaOH + H₂. (Molar mass of Na = 23 g/mol, Molar volume of gas at STP = 22.4 L/mol)

Answer: 19.6 liters

Question 1: Describe one industrial application of hydrogen and explain its significance.

Answer: Hydrogen is used in the Haber process to synthesize ammonia for fertilizers, which is vital for agriculture and food production. Its use helps increase crop yields and supports global food security.

Question 2: Explain how hydrogen fuel cells work and one advantage of using hydrogen as a clean energy source.

Answer: Hydrogen fuel cells generate electricity by combining hydrogen with oxygen, producing water as the only emission. They provide a clean, efficient energy source that reduces pollution and reliance on fossil fuels.