Answer:
Nitrogen is so vital because it is a major component of chlorophyll, the compound by which plants use sunlight energy to produce sugars from water and carbon dioxide (i.e., photosynthesis). It is also a major component of amino acids, the building blocks of proteins. Without proteins, plants wither and die.
Answer:
Specialized cells because they preform a specific function
Since it has 4 protons, it must have an atomic number of 4. (That makes it beryllium.)
Since it has a 4 protons and 5 neutrons, it has a mass number of 9.