The correct answer is: D. chemical property
Hydrogen is the most abundant element in the universe, but it is not found in its pure form on Earth. It is usually found in combination with other elements, such as oxygen in water or carbon in methane. This makes it difficult and expensive to extract hydrogen from its natural sources.
The main chemical property of hydrogen that makes it difficult to produce is its high reactivity. Hydrogen is highly flammable and can easily react with other elements to form new compounds. This makes it difficult to store and transport hydrogen safely.
Another challenge in hydrogen production is the energy required to separate hydrogen from its natural sources. This energy can come from fossil fuels, nuclear power, or renewable sources such as solar and wind power. However, the cost of producing hydrogen from these sources is still high.
Despite the challenges, hydrogen production is an important goal for the future. Hydrogen is a clean and efficient fuel that can help reduce greenhouse gas emissions. It is also a potential source of energy for fuel cells, which can be used to power vehicles and other equipment.
The other options are incorrect because:
- A. weight is not a major problem in hydrogen production. Hydrogen is the lightest element in the universe, so it is relatively easy to transport.
- B. valency is the number of electrons that an atom can share or donate in a chemical bond. Hydrogen has a valency of 1, which is not a major problem in hydrogen production.
- C. atomicity is the number of atoms in a molecule. Hydrogen has an atomicity of 1, which is not a major problem in hydrogen production.