quasars.
quasars.
quasars.
Smaller galaxies do. Larger galaxies contain billions or even trillions of stars.
None. Galaxies on the other hand do contain planets
ummmm, galaxies can have galaxies in them unless they combine, also, we don't know, the universe is infinite and we have ye to see beyond our local galaxy cluster... sorry but that is an impossible question (although if the universe is infinite then nothing is quite impossible...)
Galaxies can be classified into three main sizes: dwarf galaxies, which are small and contain less than a few billion stars; Milky Way-sized galaxies, which are intermediate in size and contain a few hundred billion stars; and giant galaxies, which are massive and can contain trillions of stars.
Spiral and irregular galaxies.
yes
Galaxy
Yes. Some spiral galaxies do contain at least 1 trillion stars.
Red giant is the largest and the brightest.
Rigel is the brightest star in Orion, Betelgeuse is the 2nd brightest