Answer:
(4) 266 moles
Explanation:
We have Dinitrogen Pentoxide N2O5
6.41*10^25 molecules are given
No of Moles of N2O5 = 
= 
= 106.5 mol
Now using Unitary Method
2 Mole of Nitrogen pentoxide require 5 mole of Oxygen to form N2O5
1 mole of N = 
In 106.5 mole of N = 
= 266.25 mole
So, 6.41*10^25 molecules of N2O5 will require 266.25 mole of Oxygen atoms.
Answer:
I don't understand what you are asking
Answer:
Summer
Explanation:
Earth's tilted axis causes the seasons. Throughout the year, different parts of Earth receive the Sun's most direct rays. So, when the North Pole tilts toward the Sun, it's summer in the Northern Hemisphere. And when the South Pole tilts toward the Sun, it's winter in the Northern Hemisphere.
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They have used added new elements to the table .
<u>Explanation:</u>
As new elements are discovered chemists add them to the period table leading to the periodic table undergoing continuous modifications. When the first periodic table in the world was formed, very few elements were known to humankind. Earlier periodic tables thus contain lesser number of elements than the modern ones.
Mendeleev's periodic table contained 63 elements arranged in the increasing order of their atomic masses. Modern periodic tables have far more number then the older ones like that of Mendeleev's and the elements are arranged in the order of their atomic numbers.
