Question

Which of the following pairs exists in free state in the earth's crust?

• A. $Na,K$
• B. $Ag,Al$
• C. $Fe,Pb$
• D. $Au,Pt$

Answer 1

The correct option is D $Au,Pt$

The metals at the top of the activity series $(K,Na,Ca,Mg$ and $Al)$ are so reactive that they are never found in
nature as free elements. The metals in the middle of the activity series $(Zn,Fe,Pb)$ are moderately reactive. They are found in the earth’s crust mainly as oxides, sulphides or carbonates.
The metals at the bottom of the activity series are the least reactive. They are often found in a free state. Ex: gold, silver, platinum and copper