The correct option is this: SODIUM IS VERY REACTIVE BECAUSE IT DOES NOT HAVE A FULL VALENCE SHELL.
For an atom to attain an octet form, it must have eight electrons in its outermost shell. Elements with eight electrons in their outermost shells are un-reactive. Sodium has only one electron in its outermost shell, this makes it to be very reactive because it is very willing to react with suitable elements in order to become stable.
Hiii
3. describe the physical characters that can be observed: phenotype
6. a specific characteristic of an organism: trait
7. a section of DNA that provides instructions for specific traits: genes
8. allele expressed in the phenotype even if only one copy is present in the genotype: dominant
hope this helped :)
