JEE Main levelSingle correct optionDifficulty 2 of 3g2075
Arrange in decreasing order of basic strength in aqueous solution using pKaH values (guanidine 13.6, methylamine 10.6, pyridine 5.2, aniline 4.6): guanidine, methylamine, pyridine, aniline.
Aaniline > pyridine > methylamine > guanidine
Bguanidine > methylamine > pyridine > aniline
Cmethylamine > guanidine > pyridine > aniline
Dguanidine > methylamine > aniline > pyridine
Answer: B
The larger the pKaH of the conjugate acid, the stronger the base: 13.6 > 10.6 > 5.2 > 4.6.