There are 3 types of atoms in an ammonia solution, NH4OH: nitrogen, hydrogen and oxygen. So, your answer in this context is A.
However, if you were considering just ammonia on its own (NH3) there are only two types of atoms, nitrogen and hydrogen.
Answer:
the chemical formula of magnesium hydroxide is Mg(OH)2
Number of moles = volume / (molar volume)
Molar volume at stp = 22.4 dm^3
Volume = no of moles × molar volume
= 0.987 × 22.4
= 22.1088 dm^3
= 22108.8 cm^3
Hope it helped!
Isn't it nitrogen AND chlorine? Both are nonmetals, and they need to gain electrons in order to bond.