Question

Which combination do not produce ${H_2}$ except-
A.$Au +$cold water
B.$cu + conc.{H_2}S{O_4}$
C.$Pt + conc.HN{O_3}$
D.All of these

Answer 1

We must have to know that hydrogen is a chemical element having the symbol H with atomic number one. And it is the lightest element which is present in the periodic table. The hydrogen is tasteless, odorless and colorless gas. And this gas is highly flammable. The hydrogen gas is mainly used to produce the electricity by using fuel cells and it is used for the preparation of fertilizer.

Complete answer:
As we know that the gold will not react with water. Because, gold is a least reactive element and the gold will not be displaced by hydrogen during the reaction if hydrogen is more reactive. Therefore, it will not produce hydrogen. But, this option is not the only correct answer. Hence, option (A) is incorrect.
If the copper is reacted with concentrated sulphuric acid, there is a formation of sulphur oxide by the reduction of sulphuric acid. And there will not be a formation of hydrogen. But other options are also correct. Hence, the option (B) is incorrect.
When platinum reacts with concentrated nitric acid, there is a formation of a metal oxide layer which is formed on the surface of the metal. And these reactions will not produce the hydrogen. Hence, option (C) is incorrect.
Among the options, there will not be a formation of hydrogen in all three reactions. Which means all of these answers are true.

Hence, the option (D) is correct.

Note:
We must have to know that the reaction of metal with water depends on its reactivity. For example, metals like gold and silver are least reactive. Hence, it will not react with water. And some of the metals are react with concentrated acids. But all the metals will not produce hydrogen. And some metal is produce the metal oxide layer in the metal surfaces like platinum. But some of the metal will liberate hydrogen gas by the reaction of metal with dilute hydrochloric acid. For eg:$Fe$ and $Mg$ .