The reaction of an alcohol with a carboxylic acid in the presence of an acid catalyst to form an ester is called:
A. Fermentation
B. Hydrogenation
C. Esterification
D. Saponification
Answer: Option C
Solution (By JKSSB Mock Tests)
Esterification is the chemical reaction where a carboxylic acid reacts with an alcohol in the presence of a strong acid catalyst (like conc. H₂SO₄) to produce an ester and water. Saponification is the reverse process, involving the alkaline hydrolysis of esters to form soap and glycerol.
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:
Henry Moseley established that the properties of elements are periodic functions of their atomic numbers, not atomic masses. This refined Mendeleev's table and resolved anomalies like Ar-K. The modern periodic table is thus based on Moseley's work. Mendeleev proposed the original table based on atomic masses. Newlands gave Law of Octaves. Meyer plotted atomic volume curve.
Explanation:
J.J. Thomson proposed the 'plum pudding' model (also called watermelon model) where the atom was considered a sphere of positive charge with electrons embedded like seeds. Rutherford's gold foil experiment disproved this by showing a dense, positively charged nucleus. Dalton proposed the indivisible atom theory. Bohr gave the model with discrete energy levels. Thomson discovered the electron but couldn't explain the nucleus.
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