1a, 3b, and 7a are examples of group on the periodic table.

Explanation : 1A, 3B and 7A are the examples of group Names on the periodic table.

The names of the groups are given in the form of numbers and alphabets. Which represents the vertical columns of the elements present in the modern periodic table.

Each group represents a somewhat similar chemical property for the elements present in it.

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