Question

1. choose the best answer using the periodic table.

what is the correct chemical formula for a compound made from li and o?
lio₂
lio
li₂o
li₃o₂

1. choose the best answer using the periodic table.

what is the name of this compound: fe₂o₃
iron (iii) oxide
iron (ii) oxide
iron (iii) oxide (ii)
iron oxide

Explanation:

Question 3

Step1: Determine oxidation states

Lithium (Li) is in Group 1, so its oxidation state is +1. Oxygen (O) in oxides usually has an oxidation state of -2.

Step2: Balance charges

Let the formula be $Li_xO_y$. The total positive charge from Li is $x(+1)$ and from O is $y(-2)$. For a neutral compound, $x(+1) + y(-2) = 0$. Substituting Li's +1 and O's -2, we get $x - 2y = 0$. The simplest ratio is when $x = 2$ and $y = 1$ (since $2(+1) + 1(-2) = 0$), so the formula is $Li_2O$.

In $Fe_2O_3$, oxygen has an oxidation state of -2. Let the oxidation state of Fe be $x$. Then $2x + 3(-2) = 0 \implies 2x - 6 = 0 \implies x = +3$. So Fe has a +3 oxidation state, and the compound is named iron (III) oxide.

Answer:

$\boldsymbol{Li_2O}$ (the option with text "Li₂O")

Question 4