Question

JEE Mains Chemistry question is in the image

Answer 1

Answer: (2) b > c > a > d

Explanation: Carboxylic acid have more acidic strength than -OH group because pKa value of Carboxylic acid less than pKa value of -OH group. pKa value of COOH is 4.0 whereas pKa value of OH is approximate 10-11 so Carboxylic acid easily Ionized at low pH value than OH group but OH have Highest acidic strength than C=CH Hydrogen because pKa value of Hydrogen in C=CH have more value than OH so Hydrogen not easily removed by from Alkene ( C=CH )

Answer 2

Find out order of acidic strength in the following compound.

1. a >. b > c > d
2. b > c > a > d
3. b > c > d > a
4. b > d > a > c

solution : According to lewis concept, an acid is proton donor while a base is proton accepter.

now for functional group, higher the tendency to donate protic ion, higher the strength of acid will be...

order of tendency of donating H⁺ ion is ..

R -COOH > R - OH > R - C ≡ CH

so acidic strength is R -COOH > R - OH > R - C ≡ CH

reason of - COOH is the most acidic is -> after donating, R - COO¯ has equivalent resonance which make it stable.

Therefore the order of acidic strength in the following compound is ; b > c > a > d .i.e., option (2) is correct choice.