The primary reason for this was that Mendeleev
didn't know that atomic numbers actually existed. Atomic numbers
were only discovered a period after Mendeleev's time. The use of X-rays made it
possible to find the atomic number, and those had not been discovered yet. <span>
<span>The periodic table was then arranged in 1913 by Henry Moseley
in an arrangement according to atomic number.</span></span>
<u>Answer:</u> The correct answer is Option 4.
<u>Explanation:</u>
There are three sub-atomic particles present in an atom. They are: electrons, protons and neutrons.
Protons constitute in each and every atom.
The charge on proton is of equal magnitude as that of electron but having opposite sign. Proton carry a positive charge and electron carry a negative charge.
Protons and neutrons, both determine the mass of an atom.
Mass of 1 proton = 1.007276 u
Mass of 1 neutron = 1.008664 u
Mass of 1 electron = 0.00054858 u
Mass of proton is almost same as that of neutron but is more than the mass of electron.
Hence, the correct answer is Option 4.
Answer:
full moon
Explanation:
....ur welcome..............
Hehehehwgwgw. Be the hardest thing ever for a long day and I have a windows
