What do the number of electrons in an atoms valence shell determine?

Molten iron fills a mould, which has a volume of 200 cm cubed. calculate the volume when the iron cools and solidifies.

An electron and a proton have the same kinetic energy upon entering a region of constant magnetic field and their velocity vectors are perpendicular to the magnetic field. suppose the magnetic field is strong enough to allow the particles to circle in the field. note: you'll need to look up the masses for an electron and proton. 1) what is the ratio of the radii of their circular paths rp/re?

Because air contracts as it cools, the air pressure inside a freezer is typically lower than on the outside. why do ice cubes inside a freezer tend to shrink over time? a. the ice dissolves oxygen from the air, forming a denser crystalline matrix. b. the ice reacts chemically with carbon dioxide in the air, forming gaseous carbon compounds. c. the ice melts, and then the liquid freezes as ice crystals on the bottom of the freezer. d. the ice sublimes, and then the water vapor deposits as ice crystals on the sides of the freezer.