Explanation

•  Mr. Patel, who is the chairman of the department, came to me yesterday. 
• - مسٹر پٹیل، جو محکمہ کے چیئرمین ہیں، کل میرے پاس آئے ●
• **
• “Who,” the subjective pronoun
•  Who functions as a subject,
• while whom functions as an object. Use who when the word is performing the action