Chose (εξελεξατο). First aorist middle (indirect), selected for himself. Israel was the chosen people.

Exalted (υψωσεν). From υψοω, late verb from υψος so often used of Christ.

When they sojourned (εν τη παροικια). In the sojourn. Late word from παροικος (sojourner, dweller, Acts 7:6) common in LXX. In N.T. only here and 1. Peter 1:17.

With a high arm (μετα βραχιονος υψηλου). Vivid picture from the LXX (Exodus 6:1; Exodus 6:6; Deuteronomy 5:15; Psalm 136:12).