Total number of nucleophiles from the following is: NH3, PhSH, (H3C)2S, H2C=CH2, OH, H3O+, (CH3)2CO, NCH3…

Step 1 — Definition of nucleophile

A nucleophile donates an electron pair to an electrophile. Species with lone pairs or $\pi$ bonds qualify.

Step 2 — Evaluate each species

1. $\ce{NH3}$: lone pair on N → nucleophile ✓
2. $\ce{PhSH}$: lone pair on S → nucleophile ✓
3. $(\ce{H3C})_2\ce{S}$: lone pair on S → nucleophile ✓
4. $\ce{H2C=CH2}$: $\pi$ electrons → nucleophile ✓
5. $\ce{OH^-}$: lone pair + negative charge → nucleophile ✓
6. $\ce{H3O^+}$: positively charged proton donor → electrophile ✗
7. $(\ce{CH3})_2\ce{CO}$: O lone pairs delocalized into C=O → poor nucleophile ✗
8. $>\ce{NCH3}$: lone pair on N → nucleophile ✓

Step 3 — Count: 5 nucleophiles → Option (a)

Key Points to Remember:

• Nucleophiles: species with available lone pairs or $\pi$ bonds
• $\ce{H3O^+}$: electrophile (Lewis acid)
• Carbonyl O lone pairs are delocalized → poor nucleophile
• $\pi$ bonds (alkenes) act as nucleophiles in electrophilic addition