Answer : The number of iron atoms present in each red blood cell are, 
Explanation :
First we have to calculate the moles of iron.
Now we have to calculate the number of iron atoms.
As, 1 mole of iron contains 
number of iron atoms
So, 0.0519 mole of iron contains 
number of iron atoms
Now we have to calculate the number of iron atoms are present in each red blood cell.
Number of iron atoms are present in each red blood cell = 
Number of iron atoms are present in each red blood cell = 
Number of iron atoms are present in each red blood cell =
Therefore, the number of iron atoms present in each red blood cell are,
Answer: The last electron will be filled in first orbital of 3p sub-shell.
Explanation: Filling of electrons in orbitals is done by using Hund's Rule.
Hund's rule states that the electron will be singly occupied in the orbital of the sub-shell before any orbital is doubly occupied.
For filling up of the electrons in Sulfur atom having 16 electrons. First 10 electrons will completely fill according to Aufbau's Rule in 1s, 2s and 2p sub-shells and last 6 electrons are the valence electrons which will be filled in the order of 3s and then 3p.
3s sub-shell will be fully filled and the orbitals of 3p sub-shell will be first singly occupied and then pairing will take place. Hence, the last electron will be filled in the first orbital of 3p-sub-shell.
Antoine Henri Becquerel discovered radioactivity when he was studying
X- rays.
He had been studying phosphorescent uranium ores and hypothesized that they might absorb sunlight and reemit it as X-rays.
His hypothesis was wrong, but his experiments led to the discovery of <em>natural radioactivity</em>.
This is false. The amount of electrons in lithium (Li) is not 7, it is 3. There are 3 electrons in lithium.
