Question

Which one of the following statements explains why elements Li, Be, and B have low cosmic abundance?

• A. These elements have low masses and hence, they break apart easily
• B. These elements have low binding energies which makes them unstable at high temperatures at the core of stars
• C. The low abundance of these elements is a unique feature of big stars with masses greater than 10 times that of our Sun
• D. These elements are highly reactive and hence, unstable

Hint:

Light elements like Li, Be, and B are rare in the universe because their nuclei are unstable at high temperatures, leading to their destruction in stellar interiors.

Answer 1

The Correct Option is B

Step 1: Understanding the cosmic abundance of elements.
Li, Be, and B are light elements that have low cosmic abundances. This is primarily due to their instability at high temperatures. The binding energies of their atomic nuclei are relatively low, meaning that at the extreme temperatures and pressures found in the cores of stars, these elements are more easily destroyed.

Step 2: Evaluating the options.
Option (A) is incorrect because the low masses of these elements do not directly lead to their low cosmic abundance; rather, it's their instability at high temperatures.
Option (B) is correct as it explains that the low binding energies of these elements cause them to be unstable at high stellar temperatures, preventing them from being abundantly formed.
Option (C) is incorrect because the low abundance of Li, Be, and B is not specific to large stars but is a general feature of the universe.
Option (D) is incorrect because while these elements are reactive, their low abundance is primarily due to nuclear instability rather than reactivity.