What does it mean when your teacher wants you to round 143 to two significant figures

If a planet rotates 360 degrees during a 24 hour time period, what does that tell us about the planet? a. the middle of the planet is in darkness b. the seasons on the planet vary every day. c. the planet runs on a 12-hour time clock. d. the temperature on the planet varies daily.

How much would the freezing point of water decrease if 4 mol of sugar were added to 1 kg of water(k=1.86 c/mol/kg for water and i=1 for sugar

An electron moved from shell n = 2 to shell n = 1. what most likely happened during the transition? a fraction of a photon was added. a photon of energy was absorbed. a fraction of a photon was removed. a photon of energy was released.