C is the correct answer since it outputs and inputs chemicals
Answer: sound waves
Explanation: Of the three mediums (gas, liquid, and solid) sound waves travel the slowest through gases, faster through liquids, and fastest through solid
<u>Answer:</u> The chemical formula of Iron (III) sulfate is 
<u>Explanation:</u>
Iron is the 26th element of periodic table having electronic configuration of ![[Ar]3d^64s^2](https://tex.z-dn.net/?f=%5BAr%5D3d%5E64s%5E2)
.
To form 
ion, this element will loose 3 electrons.
Sulfate ion is a polyatomic ion having chemical formula of 
By criss-cross method, the oxidation state of the ions gets exchanged and they form the subscripts of the other ions. This results in the formation of a neutral compound.
So, the chemical formula for Iron (III) sulfate is
First, we are discussing reversible reactions here, since the reaction is proceeded in both directions forming both reactants and products.
The reaction is symbolized as:
A + B <.........> C + D
The first given is:
The rate of appearance of D is twice the disappearance of A
This means that the coefficient of D in the reaction is twice the coefficient of A
The second given is:
The rate of appearance of D is one third the disappearance of B.
This means that the coefficient of D in the reaction is 1/3 that of B. This also means that the coefficient of B is 3 times that of D.
Combining these two pieces of information, we will find that the best equation that resembles this scenario is:
<span>A + 6 B <.........> C + 2 D </span>
Answer:
D. -120.9 kJ
Explanation:
According to Hess's law ,the total enthalpy change for a reaction is the sum of all changes regardless of the stages or the steps of the reaction.
....(1)
(this reaction should be reversed in order to reach the required reaction )
On reversing the reaction the sign of 
get reversed.
(In this case change sign from '-' to'+'. Hence = + 65 kJ)
....(1)
......(2)
Adding equation (1) and (2)
![Ca(OH)_{2} + 2HCl \rightarrow CaCl_{2} + 2H_{2}O[tex][tex]Delta H = - 186 + 65 = - 121\kJ](https://tex.z-dn.net/?f=%3Cstrong%3ECa%28OH%29_%7B2%7D%20%2B%202HCl%20%5Crightarrow%20CaCl_%7B2%7D%20%2B%202H_%7B2%7DO%3C%2Fstrong%3E%5Btex%5D%3C%2Fp%3E%3Cp%3E%5Btex%5D%3Cstrong%3EDelta%20H%20%3D%20-%20186%20%2B%2065%20%3D%20-%20121%5CkJ%3C%2Fstrong%3E)
(It is nearly equal to -120.9 kJ)
