After World War 1, Britain formed iraq as a protectorate and then used the Jordan river to divide the rest of its protectorate into

The correct answer is Palestine and Transjordan.

Explanation:

After World War I, Britain formed Iraq as a protectorate and then used the Jordan River to divide the rest of its protectorate into Palestine and Transjordan.

The main reason behind forming Iraq as a protectorate and then dividing the rest of it was because most of the area of Transjordan and Palestine was occupied by Arabic people and Jews respectively and they were thought to be growing every year.