Which labels belong in the regions marked X and Y? A. X: Absorbs energy from the core
Y: Takes longer for photons to move through
B. X: Releases energy to the photosphere
Y: Takes longer for photons to move through
C. X: Takes longer for photons to move through
Y: Absorbs energy from the core
D. X: Takes longer for photons to move through
Y: Releases energy to the photosphere

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.