Question

Which is not an essential element for plants?

• A. Iron
• B. Potassium
• C. Zinc
• D. Na$/$Ba$/$Cd$/$Al$/$Pb

Answer 1

The correct option is D Na$/$Ba$/$Cd$/$Al$/$Pb

16 elements are found to be essential. They are C, H O N P K S Mg Ca Fe B Mn Cu Zn Mo Cl. Recently four more elements have been added to the list. They are silicon, cobalt, vanadium and nickel. So the total number of essential elements is considered to be 20 instead of 16. Na/Ba/Cd/Al/Pb are not essential at all. Thus the correct answer is option D).