Which element did Dmitri Mendeleev predict to exist before it was discovered, referring to it as 'eka-silicon'?

• A. Scandium
• B. Technetium
• C. Germanium
• D. Gallium

Answer: (C)

Verified step by step guidance

1. Understand that Dmitri Mendeleev created the periodic table and predicted the existence of elements that had not yet been discovered by leaving gaps in his table.
2. Recognize that Mendeleev used the prefix 'eka-' (meaning 'one beyond' in Sanskrit) to name these predicted elements based on their position relative to known elements. For example, 'eka-silicon' means the element one period below silicon in the same group.
3. Identify the element directly below silicon in the periodic table, which belongs to the same group and shares similar chemical properties.
4. Recall that the element Mendeleev predicted as 'eka-silicon' was later discovered and named Germanium.
5. Conclude that the correct answer to the question is Germanium, as it matches Mendeleev's prediction for 'eka-silicon'.