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
The particles of gases have more kinetic energy than liquids and gases.
Explanation:
- We know that in case of solids the molecules are very tightly packed , in case of liquids the molecules are loosely packed and lastly in case of gases the molecules are very loosely packed.
- As we known in case of solids energy present is very less and in case of liquids energy present is more than solids and lastly in case of gases the energy present is most.
- Gases have more kinetic energy because the particles present in gaseous form can move easily without any obstruction.
Answer:
Boron. The answer is boron.