No.
No. Sirius is a two-star system consisting of a white main sequence star and a white dwarf.
No, a white dwarf is not considered a main sequence star. A main sequence star is a star that is still fusing hydrogen in its core. A white dwarf is the remnant of a low to medium mass star in which fusion has stopped.
Sirius is not a single star but a binary star system consisting of a white main sequence star and a white dwarf.
False. The sun is a yellow main sequence star.
Neither, it is a main sequence star.
white dwarf. unless you count black dwarf of which none have been observed, only theorized.
None of those is a main sequence star.
No. A dwarf star is a small star. A white dwarf is just one particular type of dwarf star, but there are other types.
Main sequence stars are bigger.
Depending on the size of the blue-white star it may be a white dwarf, a main sequence or even a supergiant star.
White dwarf
A Main Sequence star and a White Dwarf.