The Contact process is used for the manufacture of: MCQ with Answer and Explanation

Explanation:
The Wurtz reaction involves the reaction of an alkyl halide with sodium metal in dry ether to form a higher alkane. For example, two molecules of methyl chloride react with two sodium atoms to form ethane (C2H6) and sodium chloride. It is primarily used to synthesize symmetrical alkanes with an even number of carbon atoms.

Explanation:
Across a period, the number of electron shells remains the same, but the nuclear charge (protons) increases. The added electrons enter the same valence shell, so the effective nuclear attraction on the electrons increases, pulling them closer and shrinking the atomic radius. Down a group, radius increases due to addition of shells. Electron-electron repulsion alone does not account for the trend. Atomic mass generally increases across a period.

Explanation:
Hydration of cement is exothermic (heat of hydration). In large concrete pours, this heat can cause thermal cracking. Cooling is sometimes needed.