3 verses have
if
in Edition Clear Qur'an by Talal Itani / At-Tur (The Mount)

52:34So let them produce a discourse like it, if they are truthful.

52:44Even if they were to see lumps of the sky falling down, they would say, “A mass of clouds.”

52:49And glorify Him during the night, and at the receding of the stars.