Answer:
27.336
Explanation:
The atomic mass is the weighted average of the atomic masses of the isotopes. Simply multiply each isotopes's atomic mass by its relative abundance, then sum the results.
m = 0.8233 × 26.975 + 0.1767 × 29.018
m = 27.336
Exactly what the first person said. Hope this helps!
Answer:
Gravitational tugs from orbiting planets don't affect the motion of a star. The star, being much larger than the planet, has a much smaller orbit. But it does move slightly. Explain how alien astronomers could deduce the existence of planets in our solar system by observing the Sun's motion.