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:
The number, such as 98.7 FM, of a radio station represents:
- <u>the frequency in which is transmitted the radio signal</u>.
Explanation:
<em>The radio FM is the modulated frequency, which means that all the information is sent by just a signal, with different frequencies which difference them</em>, <u>the radio FM use the frequencies from 88 MHz until 108 Mhz (MHz is a measuring unit for the frequency), with a minimal space among them of 0.2 MHz</u>, this last means that you could find a signal in 88.0 MHz, and the next should be 88.2 MHz, next 88.4 MHz and so (at least, regularly the space between two frequencies is more than 0.2 MHz).
C is the answer because he wants to know if less force is needed to pull on a slippery surface which reduces friction