Cesium- 137 has a half life of 30 years. If it disintegrates over a period of 90 years, how much (%) remains? How much (%) decayed

In the reading, yao chen-yuan describes traveling to deliver a message. why was he willing to risk danger to travelto tientsin? he wanted to the boxers with their cause

2. how is heavy water different from normal water

Three cards with holes are arranged in a straight line. a light is shined through the first card’s hole and travels through all three cards. what does this tell you about light rays? a) that light is reflected b) that light is refractive c) that light travels in a straight line d) that light does not travel in a straight line