1) in periodic acid (HIO₄), iodine has oxidation number +7, hydrogen has oxidation number +1, oxygen has -2, compound has neutral charge:
+1 + x + 4 · (-2) = 0.
x = +7.
2) in molecule of iodine (I₂), iodine has oxidation number 0, because iodine is nonpolar molecule.
3) in sodium iodide (NaI), iodine has oxidation number -1, sodium has oxidation number +1:
+1 + x = 0.
x = -1.
4) in iodic acid (HIO₃), iodine has oxidation number +5, hydrogen has oxidation number +1, oxygen has -2, compound has neutral charge:
+1 + x + 3 · (-2) = 0.
x = +5.
<h3>Answer:</h3>
18.75 grams
<h3>Explanation:</h3>
- Half-life refers to the time taken by a radioactive material to decay by half of the original mass.
- In this case, the half-life of element X is 10 years, which means it takes 10 years for a given mass of the element to decay by half of its original mass.
- To calculate the amount that remained after decay we use;
Remaining mass = Original mass × (1/2)^n, where n is the number of half-lives
Number of half-lives = Time for the decay ÷ Half-life
= 40 years ÷ 10 years
= 4
Therefore;
Remaining mass = 300 g × (1/2)⁴
= 300 g × 1/16
= 18.75 g
Hence, a mass of 300 g of an element X decays to 18.75 g after 40 years.
The soup water would turn into soap.
Answer:true
Explanation:
definition of atomic number
Answer: The value of 
for the weak acid is 
.
Explanation:
First, we will calculate the molarity of HA as follows.
[HA] = 
= 
= 0.015
At equilibrium,
Initial: 0.015 0 0
Change: -x +x +x
Equilibm: 0.015 - x x x
It is given that, at equilibrium
[HA] = 0.015 - x = 0.013
- x = 0.013 - 0.015
= 0.002
Now, expression for of this reaction is as follows.
![k_{a} = \frac{[A^{-}][H_{3}O^{+}]}{[HA]}](https://tex.z-dn.net/?f=k_%7Ba%7D%20%3D%20%5Cfrac%7B%5BA%5E%7B-%7D%5D%5BH_%7B3%7DO%5E%7B%2B%7D%5D%7D%7B%5BHA%5D%7D)
= ![\frac{x^{2}}{[HA]}](https://tex.z-dn.net/?f=%5Cfrac%7Bx%5E%7B2%7D%7D%7B%5BHA%5D%7D)
= 
=
Thus, we can conclude that the value of for the weak acid is .
