The most stable carbocation among the following is-
1. \(({CH_3})_3C\overset{+}{C}H_2\)
2. \(({CH_3})_3\overset{+}{C}\)
3. \({CH_3}CH_2\overset{+}{C}H_2\)
4. \(({CH_3})\overset{+}{C}HCH_2CH_3\)

${\mathrm{O}}_2{\mathrm{NCH}}_2{\mathrm{CH}}_2{\mathrm{O}}^{-}$ is more stable than ${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{O}}^{-}$ because :

Alkyl groups act as electron donors when attached to a π system due to-
1. Inductive effect
2. Mesomeric effect
3. Resonance
4. Hyperconjugation

The effect that can explain the given order of acidity of the carboxylic acids is-

Cl₃CCOOH > Cl₂CHCOOH > ClCH₂COOH

1. +I effect

2. -I effect

3. +E effect

4. -E effect