How many moles are in 4.33 x 10^25 formula units of NaCl

Which of the following shapes would represent a molecule with two bonded atoms and 3 lone pairs on only one of them , trigonal planar , bent , trigonal pyramidal , linear

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.

Which of the four hypothetical substances you investigated would be most harmful to living organisms? 50 points!