Which son of Jehoash (Joash) became king of Israel in Samaria?

Answer: Jeroboam

Jeroboam son of Jehoash succeeded his father and reigned in Samaria forty-one years.

“And Jehoash rested with his fathers and was buried in Samaria with the kings of Israel. And his son Jeroboam reigned in his place. In the fifteenth year of the reign of Amaziah son of Joash over Judah, Jeroboam son of Jehoash became king of Israel, and he reigned in Samaria forty-one years.”— 2 Kings 14:16, 14:23 (BSB)