Question

Action of water or dilute mineral acids on metals can give
A. Monohydrogen
B. Tritium
C. Dihydrogen
D. Trihydrogen

Answer 1

Hint: Highly reactive or moderately reactive metals normally reacts with water, producing hydrogen and metal hydroxide when they are in contact with water. But treating them with dilute mineral acids, metals form a salt with hydrogen. Because they can easily lose their valence electrons to form a positive ion.

Complete Step by Step Answer:
Metals at the top of the periodic table are normally the most reactive and can react with water as well as with dilute mineral acids. Each of these metals can easily lose a negatively charged electron from its outermost valence shell, thereby producing positively charged ions. Some metals give up their valence electrons more easily than other metals and these are more reactive metals. The more the metals will be reactive, the faster will be the reaction.

When a metal reacts with water it produces dihydrogen and metal hydroxide. For example, Alkali metal, sodium (Na) reacts with water to form sodium hydroxide (NaOH) and dihydrogen (${{H}_{2}}$) which can be observed in the form of bubbles in the solution. The reaction is very much vigorous and violent.
 $2Na(s)+2{{H}_{2}}O(l)\to 2NaOH(aq.)+{{H}_{2}}(g)$

But when they react with dilute mineral acids such as dilute hydrochloric acid (HCl), they form dihydrogen and metal salt. For example, sodium reacts with HCl to form sodium chloride (NaCl) and dihydrogen.
$2Na(s)+2HCl(aq.)\to 2Nacl(aq.)+{{H}_{2}}(g)$
The action of water or diluting mineral acids on metals can give dihydrogen.
Thus, option (c) is correct.

Note: Metals at the bottom of the periodic table for example silver, gold, platinum, etc are generally unreactive and are stable in water and dilute acids. Whereas tin, iron, and zinc are less reactive metals that react only with dilute acid not with water as they are placed below the spectrochemical series and are less reactive than hydrogen.