Can't say i can answer this. :/
Atomic number. give me brainliest please
Answer:

Explanation:
Empirical formula of ionic compound formed by two ions
and
is
(for
) of AB (for x = y)
The above empirical formula is in accordance with charge neutrality principle
Here each cation (
and
) can form two ionic compounds by combining with two given anions (
and
).
So the four ionic compounds are: 
Answer is: volume of helium is 244.72 liters.
m(He) = 43.7 g.
n(He) = m(He) ÷ M(He).
n(He) = 43.7 g ÷ 4 g/mol.
n(He) = 10.925 mol.
V(He) = n(He) · n(He).
V(He) = 10.925 mol · 22.4 L/mol.
V(He) = 244.72 L.
Vm - molar volume at STP.
n - amount of substance.
Answer:
(B) the energy required to break apart one mole of an ionic compound into its gaseous ions
Explanation:
Lattice energy is the energy that would be obtained from the formation of an ionic compound from its gaseous ions. Therefore, the reverse process that responds the question would be the energy required to break apart an ionic compound and convert its component atoms into gaseous ions.
Lattice energy provides a measure of the stability of an ionic compound. When the ions bind to form the crystalline structure, heat (energy) is released. To break the ionic compound into the ions that form it, it is necessary to provide an energy equal to that released when formed, i.e. the lattice energy.