In which orbitals would the valence electrons for selenium (se) be placed?

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.

We are hoping to create 5.72 grams of glucose. the plant was given 4.75 liters of co2 and 2.81 g of h20. which reactant was the limiting reagent? how much excess mass did we have of the other reactant?

Apound is approximately 0.45 kilogram. a persons weighs 87 kilograms. what is the persons’s weight, in pounds, when expressed to the correct number of significant figures