Lab investigator: chemical reactions cannot be used for?

a. building and balancing chemical equations
b. gathering information about elements
c. viewing any chemical reaction in a laboratory
d. viewing some chemical reactions in a laboratory

2. select all that apply
magnesium is
a. dangerous to look at when it burns.
b. found in freshwater lakes.
c. used in photography, fireworks, and flares.
d. a compound made up of two separate elements.
3. the result of a chemical reaction is called
a. the reactant.
b. the element.
c. the compound.
d. the product.

The first element on the periodic table of elements is carbon. a. true b. false

The atomic radius of sodium is 186 pm and of chlorine is 100 pm. the ionic radius for na+ is 102 pm and for cl– is 181 pm. in going from na to cl in period 3, why does the atomic radius decrease while the ionic radius increases? a. the inner electrons in the sodium cation shield its valence electrons more effectively than the inner electrons in the chloride anion do. b. the inner electrons shield the valence electrons more effectively in the chlorine atom than in the chloride anion. c. the outermost electrons in chloride experience a smaller effective nuclear charge than those in the sodium cation do. d. the outermost electrons in chloride experience a larger effective nuclear charge than those in the sodium cation do. e. monatomic ions are bigger than the atoms from which they are formed.

What is the number of moles of chemical units represented by 9.03x10^24? and how do i show work? (dumb it down )