<u>Answer:</u> When the enthalpy of this overall chemical equation is calculated, the enthalpy of the second intermediate equation is halved and has its sign changed.
<u>Explanation:</u>
Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.
According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.
The overall chemical reaction follows:

The intermediate balanced chemical reaction are:
(1)
(2)

The expression for enthalpy of the reaction follows:
![\Delta H^o_{rxn}=[1\times (\Delta H_1)]+[\frac{1}{2}\times (-\Delta H_2)]](https://tex.z-dn.net/?f=%5CDelta%20H%5Eo_%7Brxn%7D%3D%5B1%5Ctimes%20%28%5CDelta%20H_1%29%5D%2B%5B%5Cfrac%7B1%7D%7B2%7D%5Ctimes%20%28-%5CDelta%20H_2%29%5D)
Hence, when the enthalpy of this overall chemical equation is calculated, the enthalpy of the second intermediate equation is halved and has its sign changed.
Density = mass/volume = 80 g/10cm³ = 8 g/cm³
Its air and water. if its multiple choice
The given question is incomplete. The complete question is :
In each row check off the boxes that apply to the underlined reactant. The underlined reactant acts as a... (check all that apply)
1. 
here underlined is 
A. Brønsted-Lowry acid
B. Brønsted-Lowry base
C. Lewis acid
D. Lewis base
2. 
Here underlined is 
A. Brønsted-Lowry acid
B. Brønsted-Lowry base
C. Lewis acid
D. Lewis base
3. 
Here underlined is 
A. Brønsted-Lowry acid
B. Brønsted-Lowry base
C. Lewis acid
D. Lewis base
Answer: 1. Brønsted-Lowry acid
2. Lewis base
3. Brønsted-Lowry base
Explanation:
According to the Bronsted Lowry conjugate acid-base theory, an acid is defined as a substance which donates protons and a base is defined as a substance which accepts protons.
According to the Lewis concept, an acid is defined as a substance that accepts electron pairs and base is defined as a substance which donates electron pairs.
1. 
As
is donating a proton , it acts as a bronsted acid.
2. 
As
contains a lone pair of electron on nitrogen , it can easily donate electrons to
and act as lewi base.
3. 
As
is accepting a proton , it acts as a bronsted base.