Answer:
0.00944
Explanation:
Xenon mass number on the periodic table: 131.29
Oxygen mass number: 16.00
Add them to find the molar mass of xenon trioxide: 131.29+3(16) = 179.29g/mol
Convert this to moles

Potassium (K) is in Group I of the periodic table, and elements in the same column (period) are similar. Sodium (Na), or lithium (Li) are similar.
They are arranged in shells
Answer: The coefficient for the diatomic oxygen (O2) is 3.
Explanation:
To know the coefficient for the diatomic Oxygen, we need to balance the equation.
Fe + O2 -------> Fe2O3
LHS of the equation; Fe = 1 , O2 = 1
RHS of the equation; Fe = 2 , O = 3
∴ Multiply 'Fe' on the LHS of the equation by 4 and O2 by 3
Doing that will give the balance equation which is;
4 Fe + 3 O2 --------> 2 Fe2O3
The coefficient for the diatomic oxygen (O2) as seen from the equation is 3.