I think that the sun is the center of the universe, not a human being. Everything revolves around the sun, not someone. U know when to sleep, when the time is, and when to wake up based on the sun. All the planets revolve around it. This is why I think the sun is the center of the universe, not a human being.
The answer is a. Cluster. Because they contain ten to thousands of individual galaxies.
The Period Table of Elements has more elements that have been discovered since Mendeleyev's time.
In the modern table the elements are arranged with increasing atomic number. In Mendeleyev's table, they were arranged with increasing atomic weight.
Explanation:
Atomic number means the number of protons an atom holds. Whereas mass number equals (number of protons + number of neutrons).
The given figure shows that there are 9 neutrons and 8 protons.
Therefore,
mass number of the atom = number of protons + number of neutrons
= 8 + 9
= 17
Hence, mass number of the atom is 17 and atomic number of the atom is 8.
