Tag: science & technology

B is the chemical symbol for Boron, which has atomic number 5. It is the first element in period 2 that is not a metal (metalloid). The atomic number represents proton count.

F is the chemical symbol for Fluorine, which has atomic number 9. It is the first element in period 2 (the halogens). Fluorine is the most electronegative element on the periodic table.

Mg is the chemical symbol for Magnesium, which has atomic number 12. It is an alkaline earth metal in period 2, group 2. Magnesium is essential for chlorophyll in plants.

P is the chemical symbol for Phosphorus, which has atomic number 15. It is in period 3, group 15 (pnictogens). Phosphorus exists as white and red allotropes and is essential for DNA and ATP.

S is the chemical symbol for Sulfur, which has atomic number 16. It is in period 3, group 16 (chalcogens). Sulfur is a yellow non-metal essential for proteins and forms compounds like sulfuric acid.

Cl is the chemical symbol for Chlorine. Its atomic number is 17, representing the number of protons in its nucleus. 13 is Aluminum, 15 is Phosphorus, and 19 is Potassium.

Na is the chemical symbol for Sodium, which has atomic number 11. It is an alkali metal in period 3, group 1. Sodium is highly reactive with water and is essential for nerve function in living organisms.

A valid email address must contain the '@' symbol and a domain name with extension. Option C '[email protected]' follows this correct format with username, @ symbol, and domain with .com extension. Option A lacks '@', B is a website URL, and D is missing the domain extension.