Which of the following elements is most likely to be brittle?

• A. Cobalt
• B. Selenium
• C. Zinc
• D. Platinum

Answer: (B)

Verified step by step guidance

1. Understand the concept of brittleness: Brittleness is a property of materials that break or shatter easily under stress without significant deformation. In elements, brittleness is often associated with nonmetals or metalloids rather than metals.
2. Identify the types of elements given: Cobalt, Zinc, and Platinum are metals, while Selenium is a nonmetal or metalloid. Metals tend to be malleable and ductile, meaning they are less likely to be brittle.
3. Recall the general properties of metals versus nonmetals: Metals like Cobalt, Zinc, and Platinum usually have metallic bonding, which allows atoms to slide past each other, making them less brittle. Nonmetals like Selenium have covalent or directional bonding, which can make them more brittle.
4. Compare the elements based on their position in the periodic table and typical physical properties: Selenium, being a nonmetal/metalloid, is more likely to be brittle compared to the metallic elements listed.
5. Conclude that Selenium is the most likely to be brittle among the options because of its nonmetallic character and bonding nature.