Answer:
B.
Explanation:
Si is an element.
A compound is 2 different elements combined. H2O and NaCl fit this requirement, so they are compounds. They cannot be elements because they are not single elements like Si.
C — all others endanger you.
Reactivity.
All the others are examples of a physical property.
The answer is: Convalent. i think
Answer:
The answer to your question is: Boron
Explanation:
Helium has 2 electrons in the first energy level and does not have any electron in the second energy level.
<u>Boron </u><u>it has 2 electrons in the first energy level and three electrons in the second energy level.</u>
Beryllium has 2 electrons in the first energy level and 2 electrons in the seond energy level.
Carbon has 2 electrons in the first energy level and 4 electrons in the third energy level.