All the elements in a particular group of the periodic table have the same number of. a. electrons.. b. energy levels.. c. valence electrons.. d. protons..

C

Explanation:

Every element within a group will have similar properties to every other element in that group (eg. Florine will have similar properties to Chlorine and Bromine, because all the elements are in group 17). One common property every element in a group will share is the number of valence electrons.

Valence electrons are the electrons in the outermost orbital of the atom, and these are the electrons that will be shared when an atom bonds to another atom.

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

                                  = 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g