The reaction includes the single replacement reaction and redox
<h3>Further explanation</h3>
Single replacement : one element replaces another element in a compound
A + BC ⇒ AC + B
The oxidation-reduction reaction or abbreviated as Redox is a chemical reaction in which there is a change in oxidation number
3CuCl + 2Al => 3Cu + 2AlCl₃
Al replacing Cu in the CuCl compound
3Cu²⁺ + 6e⁻⇒ 3Cu reduction(oxidation number from +2 to 0)
2Al⇒2Al³⁺+6e⁻ oxidation(oxidation number from 0 to +3)
Answer : The hydroxide ion concentration of a solution is, 
Explanation :
As we know that
dissociates in water to give hydrogen ion
and carbonate ion
.
As, 1 mole of
dissociates to give 1 mole of hydrogen ion 
Or, 1 M of
dissociates to give 1 M of hydrogen ion 
So, 0.200 M of
dissociates to give 0.200 M of hydrogen ion 
Now we have to calculate the hydroxide ion concentration.
As we know that:
![[H^+][OH^-]=1\times 10^{-14}](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%5BOH%5E-%5D%3D1%5Ctimes%2010%5E%7B-14%7D)
![0.200\times [OH^-]=1\times 10^{-14}](https://tex.z-dn.net/?f=0.200%5Ctimes%20%5BOH%5E-%5D%3D1%5Ctimes%2010%5E%7B-14%7D)
![[OH^-]=5\times 10^{-14}](https://tex.z-dn.net/?f=%5BOH%5E-%5D%3D5%5Ctimes%2010%5E%7B-14%7D)
Therefore, the hydroxide ion concentration of a solution is, 
Answer:
Object 2 with a density of 0.68
Explanation:
object 2 has a lower density than water so it will float
Answer:
Percent by mass of water is 56%
Explanation:
First of all calculate the mass of hydrated compound as,
Mass of Sodium = Na × 2 = 22.99 × 1 = 45.98 g
Mass of Sulfur = S × 1 = 32.06 × 1 = 32.06 g
Mass of Oxygen = O × 14 = 16 × 14 = 224 g
Mass of Hydrogen = H × 20 = 1.01 × 20 = 20.2 g
Mass of Na₂S0₄.10H₂O = 322.24 g
Secondly, calculate mass of water present in hydrated compound. For this one should look for the coefficient present before H₂O in molecular formula of hydrated compound. In this case the coefficient is 10, so the mass of water is...
Mass of water = 10 × 18.02
Mass of water = 180.2 g
Now, we will apply following formula to find percent of water in hydrated compound,
%H₂O = Mass of H₂O / Mass of Hydrated Compound × 100
Putting values,
%H₂O = 180.2 g / 322.24 g × 100
%H₂O = 55.92 % ≈ 56%
It will be Oxygen . And total 8 protons, 8 electrons and 9 neutrons are present in it.