Answer:
(a) 0.8 s
(b) t = 7.2 s
Explanation:
(a) Half life expression for second order kinetic is:
![t_{1/2}=\frac{1}{k[A_o]}](https://tex.z-dn.net/?f=t_%7B1%2F2%7D%3D%5Cfrac%7B1%7D%7Bk%5BA_o%5D%7D)
Where,
is the initial concentration = 1.0 M
k is the rate constant = 1.25 M⁻¹s⁻¹
So,

Half life = 0.8 s
(b) Integrated rate law for second order kinetic is:
![\frac{1}{[A_t]} = \frac{1}{[A]_0}+kt](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B%5BA_t%5D%7D%20%3D%20%5Cfrac%7B1%7D%7B%5BA%5D_0%7D%2Bkt)
Where,
is the final initial concentration
For 90% completion, 10% is left. so,
![[A_t]=\frac {10}{100}\times 1.0=0.1\ M](https://tex.z-dn.net/?f=%5BA_t%5D%3D%5Cfrac%20%7B10%7D%7B100%7D%5Ctimes%201.0%3D0.1%5C%20M)
So,

t = 7.2 s
Answer:
c
Explanation:
was c the correct answer or not
Hope u do well :) ik this maybe hard but you’ll get through it , the answer is D !
Question One
It's more a question of unscrambling what is there. The answer is correct.
If you look at your periodic table, there is such an element as Na which I suspect might be the problem.
It has an atomic mass of 23. It's atomic number is 11 which means it is the 11th member (by mass) on the periodic table. The other 2 are oxygen and hydrogen. So Oxygen has an atomic mass of 16 and Hydrogen has an atomic mass of 1.
Oxygen is number 8 on the periodic table and hydrogen is number 1.
Molecular Mass
Na = 23
O = 16
H = 1
Total 40, just as the answer key says. I've probably given you more than you wanted to know, but if you still have trouble, leave a note.
<span>Due to limitations on typography, I will have to describe the equation instead of actually writing it.
Crude appearance.
18 18 0
F --> O + e
9 8 1
Detailed description. Each of the 3 components have both a left superscript and a left subscript which is a superscript and a subscript to the LEFT of the main figure unlike the usual right side that you see subscripts and superscripts.
The equation will be F with an 18 left superscript and a 9 left subscript to represent Florine with atomic weight of 18 and 9 protons.
Followed by a right arrow to indicate the direction the reaction is going.
Followed by the letter O with a left superscript of 18 and a left subscript of 8 to represent Oxygen with atomic weight of 18 and 8 protons.
Followed by a plus sign to indicate more.
Followed by either the lower case letter "e" or the upper case Greek character beta with a left superscript of 0 and a left subscript of 1 or +1 to represent the positron being emitted with a positive charge and an atomic weight of 0.</span>