Which of the following is an example of a gel? MCQ with Answer and Explanation

Explanation:
The combined gas law integrates Boyle's (P₁V₁ = P₂V₂), Charles' (V₁/T₁ = V₂/T₂), and Gay-Lussac's (P₁/T₁ = P₂/T₂) laws into one equation: P₁V₁/T₁ = P₂V₂/T₂ for a fixed amount of gas. It assumes ideal behavior. When one variable is constant, the respective individual law can be derived. For changing conditions, this combined form is useful. For n moles, PV = nRT.

Explanation:
A catalyst lowers the activation energy barrier by providing a different reaction mechanism. This allows more reactant molecules to have sufficient energy to react. It does not change the thermodynamics (ΔH, equilibrium constant) or get consumed in the reaction. Enzymes are biological catalysts.

Explanation:
Natural gas (mainly methane) is a fossil fuel formed from ancient organic matter. Biogas is a renewable fuel from recent organic waste. Hydrogen is an energy carrier, not a fossil fuel. Solar energy is renewable.