Principal shell shows the main energy level, in that there are some more energy levels. This is how the atomic structure is defined according to the Quantum Mechanical model of atom. So exactly why do subshells exist and all i don't know
Answer : The half life of 28-Mg in hours is, 6.94
Explanation :
First we have to calculate the rate constant.
Expression for rate law for first order kinetics is given by:

where,
k = rate constant
t = time passed by the sample = 48.0 hr
a = initial amount of the reactant disintegrate = 53500
a - x = amount left after decay process disintegrate = 53500 - 10980 = 42520
Now put all the given values in above equation, we get


Now we have to calculate the half-life.



Therefore, the half life of 28-Mg in hours is, 6.94
Answer:
When the concentration of all the reactants increases, more molecules or ions interact to form new compounds, and the rate of reaction increases. When the concentration of a reactant decreases, there are fewer of that molecule or ion present, and the rate of reaction decreases.
Answer:
This question sadly does not make much sense, please rephrase it.
he is a good scientist because he postulated that chemical reactions resulted in the rearrangement of the reacting atoms