Question

Name two metal oxides which are water soluble.

Answer 1

Hint: We know that a metal is a material that when freshly prepared shows a lustrous appearance, they can be beaten to form sheets and they can be converted to form wires or we can say they are malleable and ductile. They can conduct electricity as they have free electrons.

Complete answer:
Metals react differently with water; some metals do not even react with water. Like sodium and potassium react vigorously with water, their reaction with cold water is violent and highly exothermic. The reaction of calcium is less violent. On the other hand, magnesium reacts with hot water.
Metals like aluminum, iron and zinc do not react with cold and hot water; they react with steam to form metal oxide and hydrogen gas. Some metals like lead, copper, silver and gold don’t even react with water. So, on the basis of reactivity of metal, metals can be arranged in order of their decreasing activities. On the basis of displacement reactions of metals with other metal salts, a reactivity series has been developed. In which some metals are highly reactive some are moderately reactive and some are least reactive.
Thus, Sodium oxide $ \left( N{{a}_{2}}O \right) $ , potassium oxide $ \left( {{K}_{2}}O \right) $ are metal oxides which are water soluble .

Note:
 Remember that the metals like copper and silver can be found in combined states even though they are least reactive. They can be found in their sulphide and oxide ores. The metals at the top of the reactivity series like $ Na,\text{ }K,\text{ }Ca,\text{ }Mg $ are so reactive that they are never found in nature as free elements.