Alkenes must undergo addition because they have easily broken tt bonds.
Markonikov's rule states in the addition of HX to an unsymmetrical alkene, the H atom bonds to the less substituted carbon atom.
alkenes are unsaturated hydrocarbons because they have fewer than the maximum number of hydrogen atoms per carbon.
Alkyl halides have good leaving groups and therefore readily undergo substitution and elimination reactions.
In hydroboration, the boron atom bonds to the substituted carbon.
Hydroxides, amines and alcoxides undergo substitution and elimination, but can do so only when the heteroatom is made into a good leaving group.
You are right, it's CA Calcium, 40.08, Group 2 and Row 4.
Answer:
I dont know the first blank but I know the second one is groups and the last one is periods.
I think it is rarefaction. But im not sure