The pinwheel-shaped spiral arms of our galaxy extend outward from the
a) interstellar matter
b) galactic bulge
c) galactic center
d) nebulae
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The one that is being described above which has a pinwheel-shaped spiral arms in the galaxy is what we call the galactic bulge. the answer to this is option b. an example of this galactic bulge is the milky way galaxy which forms like a disk with spiral arms and halo. hope this .

Answer : option a) 84explanation :

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.

Precipitate, and gas