How many elements are naturally occurring on Earth?

• A. 118
• B. 104
• C. 86
• D. 92

Answer: (D)

Verified step by step guidance

1. Understand that the question asks for the number of elements that occur naturally on Earth, meaning elements that can be found in nature without human synthesis.
2. Recall that the total number of known elements is 118, but many of these are synthetic and created in laboratories.
3. Identify that elements with atomic numbers 1 through 92 are generally considered naturally occurring, although some of these (like technetium and promethium) are very rare or found only in trace amounts.
4. Recognize that elements beyond atomic number 92 (uranium) are typically synthetic or have very short half-lives and do not occur naturally in significant amounts.
5. Conclude that the number of naturally occurring elements on Earth is 92, corresponding to all elements from hydrogen (1) to uranium (92).