The answer is D I hope this helps you !
Yes. density is a physical property that can be used to identify matter
Answer:
Hydrofluoric acid.
Explanation:
To know which of the acid is the strongest, let us determine the pka of each acid. This is illustrated below:
1. Acetic acid
Ka = 1.8x10^-5
pKa =..?
pKa = –logKa
pKa = –Log 1.8x10^-5
pKa = 4.74
2. Benzoic acid
Ka = 6.5x10^-5
pKa =..?
pKa = –logKa
pKa = –Log 6.5x10^-5
pKa = 4.18
3. Hydrofluoric acid.
Ka = 6.8x10^-4
pKa =..?
pKa = –logKa
pKa = –Log 6.8x10^-4
pKa = 3.17
4. Hypochlorous acid
Ka = 3.0x10^-8
pKa =..?
pKa = –logKa
pKa = –Log 3.0x10^-8
pKa = 7.52
Note: the smaller the pKa value, the stronger the acid.
The pka of the various acids as calculated above is given below:
Acid >>>>>>>>>>>>>>>>>> pKa
1. Acetic acid >>>>>>>>>> 4.74
2. Benzoic acid >>>>>>>> 4.18
3. Hydrofluoric acid >>>> 3.17
4. Hypochlorous acid >> 7.52
From the above illustration, we can see that hydrofluoric acid has the lowest pKa value. Therefore, hydrofluoric acid is the strongest among them.
Answer:
(A) 
(B) 
Explanation:
(A) 2NO(g) + O₂(g) → 2NO₂(g)

Now, multiplying equation (a) with 2:
⇒ 
Then equation b is reversed and multiplied with 2:

Now by adding the equation (a) and equation (b), we get:
⇒ 
⇒ 2NO(g) + O₂(g) → 2NO₂(g)
<u>Therefore, the enthalpy of the reaction:</u>


(B) 4B(s)+3O₂(g) → 2B₂O₃(s)




Now multiplying equation (b) with 2, reversing equation (a) and multiplying with 2. Reversing equation (c) and (d) and multiplying both with 6.



Now by adding the equations (a), (b), (c), (d); we get:
4B(s)+3O₂(g) → 2B₂O₃(s)
<u>Therefore, the enthalpy of the reaction: </u>

