Answer:
An atom of neon-20 has one fewer proton and two fewer neutrons than an atom of sodium-23.
Explanation:
Neon - 20 and Sodium - 23
Neon - 20
Protons = 10
Neutrons = 10
Sodium - 23
Protons = 11
Neutrons = 12
With the information above and checking the options;
An atom of neon-20 has one fewer proton and two fewer neutrons than an atom of sodium-23.
This option is correct.
Answer:
This means that the metal is more properly viewed as an array of positive ions surrounded by a “sea of mobile valence electrons.” Electrons which are capable of moving freely throughout the empty orbitals of the metallic crystal are called delocalized electrons (Figure below).
Just add up the molar masses of each element.
Molar mass of C: 12.011 g/mol
The equation says C20, which means there are 20 carbon atoms in each molecule of Vitamin A. So, we multiply 12.011 by 20 to get 240.22 g/mol carbon.
Molar mass of H: 1.0079 g/mol
The equation says C30, which means there are 30 hydrogen atoms in each molecule of Vitamin A. So, we multiply 1.0079 by 30 to get 30.237 g/mol hydrogen.
Molar mass of O: 15.999 g/mol
The equation says O without a number, which means there is only one oxygen atom in each molecule of Vitamin A. So, we leave O at 15.999 g/mol.
Then, just add it up:
240.22 g/mol C + 30.237 g/mol H + 15.999 g/mol O = 286.456 g/mol C20H30O
So, the molar mass of Vitamin A, C20H30O, is approximately 286.5 g/mol.
