Which of the following is a combination reaction? MCQ with Answer and Explanation

Explanation:
According to Graham's law, the rate of diffusion is inversely proportional to the square root of molar mass. Hydrogen (H₂) has the lowest molar mass (2 g/mol) among the options (O₂=32, N₂=28, CO₂=44), so it will diffuse the fastest under identical conditions of temperature and pressure.

Explanation:
Neutralization is the reaction of an acid with a base to produce salt and water. However, the resulting solution is not always neutral (pH 7) because the salt may undergo hydrolysis. If the acid is strong and base weak (e.g., HCl + NH₄OH), the salt (NH₄Cl) is acidic, pH < 7. If acid is weak and base strong (CH₃COOH + NaOH), salt is basic, pH > 7. Only strong acid-strong base gives pH 7.

Explanation:
Starch (polysaccharide) is a natural polymer made from glucose units. It is found in plants. Cellulose, proteins, natural rubber are natural polymers. PVC, nylon, Teflon are synthetic polymers. Natural polymers are biodegradable and renewable. Starch is used as food, in paper, and bioplastics. Synthetic polymers are often derived from petrochemicals.