Question

Metals react with cold water and give:
(A) metal oxides
(B) metal oxides and oxygen
(C) metal oxides and hydrogen
(D) metal hydroxides and hydrogen

Answer 1

Hint: Think about the reactivity series of metals and which metals react with cold water, hot water, and steam. According to this, note the products that are formed after oxidation and then answer the question.

Complete step by step solution:
How metals react with water is determined based on the reactivity series. Some of the highly reactive metals react with cold water, some metals that are less reactive need the water to be in steam before they can react with it, they do not react with either cold water or hot water. Since their reactivity is less, they will require more energy for reactions. Some metals do not react with water at all.
When metals react with water, they form either oxides or hydroxides, this can be determined based on how reactive they are. The more reactive metals usually for hydroxide with water and the less reactive elements for oxides. The reactivity series for metals is:
\[K>Na>Li>Ba>Sr>Ca>>Mg>Al>Zn>Fe>Sn>>Cu>Ag>Au>Pt\]
Out of all these metals, only the metals up to calcium can react with cold water. All the other metals after calcium either require hot water, steam, or do not react with water at all (elements after tin). From the 6 metals that react with cold water, only potassium and sodium react vigorously with water. Now, we will look at the reactions of each of these elements with water. They will be as follows:
\[\begin{align}
& 2K+2{{H}_{2}}O\to 2KOH+{{H}_{2}} \\
& 2Na+2{{H}_{2}}O\to 2NaOH+{{H}_{2}} \\
& 2Li+2{{H}_{2}}O\to 2LiOH+{{H}_{2}} \\
& Ba+2{{H}_{2}}O\to Ba{{(OH)}_{2}}+{{H}_{2}} \\
& Sr+2{{H}_{2}}O\to Sr{{(OH)}_{2}}+{{H}_{2}} \\
& Ca+2{{H}_{2}}O\to Ca{{(OH)}_{2}}+{{H}_{2}} \\
\end{align}\]
Magnesium still reacts with water to give a hydroxide, but from aluminium onwards, the metals usually give oxides after when the reactions take place.
Here, we can see that all the elemental metals involved form hydroxides when they react with water and the evolution of hydrogen will take place.

Hence, the correct answer is (C).

Note: Note that not all the metals have been mentioned in the reactivity series given only the metals up to calcium have been mentioned. After that, only the most common and prominent metals are shown.