The ground-state electronic configuration of the manganese atom, Mn, is:. A) 1s2 2s2 2p6 3s2 3p6 4s2 4d5.
B) 1s2 2s2 2p6 3s2 3p6 3d7.
C) 1s2 2s2 2p6 3s2 3p6 4s2 4p5.
D) 1s2 2s2 2p6 3s2 3p6 3d5 4s2.

A) .

Explanation:

An electronic configuration is an expression/ arrangement of the electrons in an atom or element. The principle of the orbitals are followed to write the electronic configuration of any atom or element.

At the ground state, the electrons in an atom or element are not excited, thus they are in their lowest energy state.

Manganese atom has 25 electrons, so its electronic configuration is .

1. 1 mole of anything contains 6.022x10^23 pieces  

d  

2. a  

3. c, number  

5. 1.24x10^24atoms / 6.022x10^23atoms/mole = 2moles h2 atoms  

6. fe2br3 mass = 2moles x mass fe + 3 moles x mass br  

molar mass = grams / number of moles = g/mole  

to find moles = g / molar mass  

to find mass = g = molar mass / moles

i think that the answer is c