1)
Rashi (to 7:25) cited Chazal, that each Makah remained in force for a quarter of a month (a week). If that term had already elapsed, why did Moshe have to pray for the Barad to be removed? If the time had not yet passed, then the Makah would not last for its full duration!
1.
Gur Aryeh, Maharal: Refer to 7:25:1.3:2, 7:25:1.3:3, and 7:25:1.3:4.
2)
Why did Pharaoh ask specifically for the thunderous sounds (which accompanied the hail) to cease?
1.
Refer to 9:14:1.1:1***, and also to 7:14:4:3.
