Chemistry 2 Marks Questions

Gem-Dialkoxyalkanes in which the two alkoxy groups are present on the same carbon within the chain are called ketals. These are produced when a ketone is heated with ethylene glycol in presence of dry HCl gas or p-toluenesulphonic acid (PTS).


These are easily hydrolysed by dilute mineral acids to regenerate the original ketones. Therefore, ketals are used for protection of keto groups in organic synthesis.

Sodium chloride or calcium chloride depresses the freezing point of water to such extent that it cannot freeze to form ice. Hence it melts off easily at the prevailing temperature. As depression in freezing point is a colligative property which is directly related to number of solute particles. NaCl gives 2 ions in solution while CaCl₂ gives 3 ions in solution.

Transition metals show catalytic property because of their ability to adopt multiple oxidation states. Catalysts at a solid surface involve the formation of bond between reactant molecules and atoms of the surface of the catalyst. This has the effect of increasing the concentration of the reactants at the catalyst surface and also weakening of the bonds in the reacting molecules & the activation energy is lowered, moreover transition metals can change their oxidation state. Transition metals have tendency to form reaction intermediates with suitable reactants. The reaction intermediates decompose yielding products and regenerating the original substance. The transition metals form reaction intermediates due to the presence of vacant orbitals.