Vulcanization of rubber uses: MCQ with Answer and Explanation

Explanation:
The universal gas constant R has different values depending on the units used. In SI units (Joules), R = 8.314 J/(mol·K). In L·atm, it is 0.0821 L·atm/(mol·K). Option D mixes SI and L·atm units incorrectly. The value of R is fundamental in thermodynamic calculations.

Explanation:
Metallurgy is the science and technology of extracting metals from their ores, purifying them, and preparing them for use. It involves various steps like concentration, reduction, and refining. Mineralogy is the study of minerals, and geology is the study of the Earth's physical structure.

Explanation:
Enzymes are biological catalysts that function optimally at moderate temperatures (around 35-40°C for human enzymes). Most enzymes denature and lose activity at temperatures above 50-60°C, as the protein structure unfolds. They are highly specific (lock-and-key model), protein in nature, and lower activation energy without being consumed. Some thermophilic bacteria have enzymes active at high temperatures, but typical enzymes are not stable at >100°C.