Answer: a. BaO
Explanation:
For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.
Here element barium is having an oxidation state of +2 called as 
cation and 
is an anion with oxidation state of -2. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral 
The element group which is least likely to form ions is 4A group
<u><em>explanation</em></u>
Element of group 4A has 4 valence electrons. for example Carbon which has [He] 2S2 2P2 electron configuration has 4 valence electrons.
Since 4A elements has 4 valence electrons , it means that their valence shell is half filled which is relatively stable. <em>For this reason 4A element readily form ions.</em>
Answer:
Explanation:
To convert the mass of Aluminum to atoms, we must first convert to moles by using the formula;
mole = mass/molar mass
Both evaporation and condensation are in the water cycle. evaporation is when water changes from liquid to gas meanwhile condensation is when water vapor cools and goes from gas to liquid.
