Question

Which metal does not react with water?
A. \[Cu\]
B. \[Au\]
C. Both “A” and “B”
D. \[Fe\]

Answer 1

Hint: If a metal reacts with water it will replace the hydrogen from water and make hydrogen (bubbles) and the metal oxides for example, sodium reacts rapidly with cold water.

Complete step-by-step answer:
We know that when metals react with water and produce a metal oxide and hydrogen gas. Metal oxides that are further soluble in water dissolve in it to further form metal hydroxide.
We know that reactivity of the metal inversely correlates to its first ionization energy. That means that if a metal has very low ionization energy then it is very reactive.
Metals react by giving out electrons so if they can lose their electrons easily then they can react very fast. Elements with high electronegativity will be very reactive.
The elements within the same group of the periodic table tend to exhibit similar physical and chemical properties. Four major factors affect reactivity of metals: nuclear charge, atomic radius, shielding effect and sublevel arrangement of electrons.
Metal reactivity relates to ability to lose electrons. In general the bigger the atom, greater the ability to lose electrons.
The greater the shielding, the greater the ability to lose electrons. So, the most reactive metal is towards the left and down.
So, above mentioned are some points on reactivity of metals. In this question \[Cu\] and \[Fe\] are of the same row elements but iron is more left than copper so it is a bit more reactive. And copper and gold are in the same column and copper is more reactive than gold. So, we place these three in order of reactivity \[Fe\]>\[Cu\]>\[Au\].

From above points we can conclude that:
“A” is the correct answer, copper does not react with water, because the oxygen in water is locked into a compound with one part oxygen and two parts hydrogen. Copper oxide is a compound from the two elements copper and oxygen.
“B” is the correct answer, because it comes at the lowest position in the reactivity series.
“D” is incorrect, because it reacts with water and it is a more reactive metal and after reacting with water it forms iron oxide.
So, the correct option is “C”.

Note: When we take a copper electrical heater, immerse it in water and heat it above 700 degree centigrade. Then copper will start forming cuprous oxide with water and this kind of reaction happens in steam boilers.