A radioactive material has a half life of a day of 30 days you begin wihy 4 grams of radioactive material jow much of thr orginal is lect uncharged after 90 days

0.5 g

Explanation:

Given data:

Half life of radioactive material = 30 days

Total mass = 4 gram

Mass left after 90 days = ?

Solution:

Number of half lives passed:

Number of half lives = Time elapsed / half life

Number of half lives = 90 days / 30 days

Number of half lives = 3

At time zero = 4 g

At first half life = 4g/2 = 2 g

At 2nd half life = 2g/ 2= 1 g

At 3rd half life = 1 g/2 = 0.5 g

the electronic configuration of an atom with eight electrons is 1s²2s²2p⁴. the orbital diagrams are shown in the figure.

as per the hunds rule:

1. electrons tend to avoid being in the same orbital as per as practicable.

2. electrons in different orbitals of the same energy will have their spin parallel.

this can be illustrated from the multiplicity of the orbitals of the atom. as there are four electrons in the p orbital and p orbital has 3 sub-shells. the electrons can be fed in different ways as shown in the figure but the correct orbital diagram will be as per the hunds rule.

explanation:

metals have excess of electrons whereas non-metals have deficiency of electrons. thus, in order to gain stability metals easily donate their electrons to the non-metals.

for example, electronic configuration of sodium is and electronic configuration of phosphorous is .

when a phosphorous atom and sodium atom combine together then sodium will donate is extra one electron to the phosphorous atom. as a result there will be formation of ionic bond between sodium and phosphorous.

the reaction will be as follows.

there, are three sodium sodium atoms and each of them will donate its one extra electron to phosphorous atom. thus, the sub-shell of phosphorous gets completely filled.  

thus, we can conclude that electrons are transferred from atoms of sodium to atoms of phosphorous. this transfer makes the sodium atoms donate one electron and the phosphorous atoms to gain one electron. as a result, the sodium and phosphorus atoms strongly attract each other.