Answer:
Ammonium hydroxide, NH₄OH
Magnesium hydroxide, Mg(OH)₂
Sodium hydroxide, NaOH
Lithium hydroxide, LiOH
Explanation:
A base is a substance which neutralizes acids to produce salt and water. Bases are hydroxide or oxides of metals. Bases may be soluble or insoluble in water. Bases generally have a bitter taste and turn red litmus paper or indicator red.
Alkalis are bases which are soluble in water. They form the hydroxide of the alkali metals or alkaline earth metals in solution and they ionize to produce hydroxide ions. They are slippery to touch and turn red litmus blue being bases.
Therefore, all alkalis are bases but not all bases are alkalis. Insoluble bases are not alkalis.
From the given chemical compounds the alkalis present in the list are:
Ammonium hydroxide, NH₄OH; since it is soluble in water and produces hydroxide ions
Magnesium hydroxide, Mg(OH)₂; since it is slightly soluble in water and produces hydroxide ions
Sodium hydroxide, NaOH; since it is soluble in water and produces hydroxide ions
Lithium hydroxide, LiOH; since it is soluble in water and produces hydroxide ions
CuO(copper oxide) is a base but not an alkali as it does not produce hydroxide ions.
Zn(OH)2 (zinc hydroxide) is amphoteric and is insoluble
MgO(magnesium oxide) is a base but not an alkali as it does not produce hydroxide ions.
Na2O(sodium oxide) is a base but not an alkali as it does not produce hydroxide ions.
CoO(cobalt oxide) is a base but not an alkali as it does not produce hydroxide ions.
