What causes an ion to have a positive charge? what causes an ion to have a negative charge?

Use a graphing calculator to solve the equation - 3 cos t = 1 in the interval from 0 ≤ theta ≤ 2 π round to the nearest hundredth.

What empire controlled most of the middle east except for a few years between 1516 and 1917, where was the capital of this empire located and what was the geographic extent of this empire?

What characteristic of the basin that feeds the congo river system affects movement in central africa? a. the center of the basin is a dense rain forest. b. it is the center of ethnic conflict in the area. c. wildlife on the savanna makes it too dangerous to travel. d. the basin is surrounded by desert.