Which of the following set of metals is never found in free state?K, Na, CaCu, AgCu, AuAu, Ag

To determine which set of metals is never found in a free state, we need to analyze the reactivity of each metal listed in the options provided. Here’s a breakdown:

1. Reactivity Series: Metals are arranged in a reactivity series from most reactive to least reactive. The more reactive a metal is, the more likely it is to be found in compound form rather than in its free state.

2. Group Analysis:

   • K (Potassium): This is a highly reactive alkali metal and is never found in a free state; it occurs in nature primarily as ionic compounds.
   • Na (Sodium): Similar to potassium, sodium is also very reactive and does not exist freely in nature.
   • Ca (Calcium): Calcium is a reactive alkaline earth metal and is typically found in the form of compounds.
   • Cu (Copper): Unlike the above, copper can be found in a free state because it is less reactive and has a tendency to be found in its metallic form, though it's often found as a compound.
   • Ag (Silver): Silver is less reactive than potassium, sodium, and calcium, and it can be found in a free state in nature.
   • Au (Gold): Gold is very unreactive and is frequently found in a free state, often in alluvial deposits.

3. Conclusion: The metals K, Na, and Ca are never found in their free state due to their high reactivity. Therefore, the set of metals that is never found freely in nature is {K, Na, Ca}.

In summary, K (Potassium), Na (Sodium), and Ca (Calcium) are all highly reactive metals and are never found in a free state, while Cu (Copper), Ag (Silver), and Au (Gold) can exist in their elemental forms.