121) A compound is soluble in conc. H₂SO₄. It does not decolourise bromine in carbon tetrachloride but is oxidised by chromic anhydride in aqueous sulphuric acid within 2 seconds, turning orange solution to blue, green and then opaque. The original compound is:

122) IUPAC name of aldol condensation product between formaldehyde and acetaldehyde is:

123) In a reaction, RCHO is reduced to RCH₃ using amalgamated zinc and conc. HCl, and warming the solution. The reaction is known as:

124) One mole of alkene X, on ozonolysis gave one mole of acetaldehyde and one mole of acetone. The IUPAC name of X is:

125) The synthesis of crotonaldehyde from acetaldehyde is an example of which reaction?