Cobalt
Lead is a brittle metallic element with 4 letters.
This metal is cobalt.
Yes, neptunium is a metallic element and can exhibit a metallic luster when polished.
Iridium
Promethium, a rare and radioactive element, typically has a metallic luster and a silvery-gray appearance. Its texture is generally smooth and metallic, similar to other metals, but it can also be somewhat brittle. Due to its radioactivity, handling promethium requires precautions to avoid exposure.
An example of an element that is not shiny and does not conduct heat and electricity well is sulfur. Sulfur is a brittle, non-metallic element that typically appears as a yellow solid. It is poor in terms of electrical and thermal conductivity, making it a good insulator. This property, along with its dull appearance, distinguishes sulfur from many metallic elements.
Actinium has a white-silvery metallic appearance.
Not known, probably a metallic appearance.
The brittle bluish-white metallic element you are referring to is most likely Bismuth (Bi). Bismuth is a chemical element with the atomic number 83 and is known for its distinctive bluish-white color. It is a brittle metal that can be easily broken or crumbled. Bismuth is also known for its low thermal and electrical conductivity. It is often used in various applications, including cosmetics, pharmaceuticals, and alloys.
Iodine is malleable when it is in crystalline form.
Metal and nonmetal be simultaneously is not possible.
Antimony is a metalloid which means that it has metallic and nonmetallic properties and it is element 51 in the periodic table lying in the diagonal metalloids in the p group. The metallic and nonmetallic properties may be, for example, that it is grey and shiny like a metal but it may also be brittle and not conduct heat and electricity like a nonmetal.