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

(N/A) $(1)$ Chlorophyll-$a$ appears blue-green in chromatograms,whereas Chlorophyll-$b$ appears yellow-green.
$(2)$ In $PS-I$,the reaction center chlorophyll-$a$ has an absorption peak at $700 \,nm$ (known as $P_{700}$),while in $PS-II$,the reaction center chlorophyll-$a$ has an absorption peak at $680 \,nm$ (known as $P_{680}$).