How many chlorophyll molecules combine to form quantasomes?

Which molecule acts as the reaction center in photosynthesis?

Which chlorophyll molecule does not possess a phytol tail?

Analogy type question:
$(1)$ Chlorophyll-$a$ : Blue-green color :: Chlorophyll-$b$ : .......
$(2)$ Chlorophyll-$a$ molecule in $PS-I$ : Absorption of $700 \,nm$ wavelength :: In $PS-II$ : .......

In the structure of chlorophyll,$.........$ is required,and for its synthesis,$.............$ is required.

Chlorophyll $a$ is present in which of the following?