Mario places 10 mL of water in a test tube and heats the liquid over a Bunsen burner for 2 minutes. After removing the test tube from the Bunsen burner, there are 6 mL of water left in the test tube. This experiment is a good example of a <span>physical change involving phase changes. </span>
Answer:
b. ΔH and ΔS are negative at all temperatures .
Explanation:
During the process of condensation ,
The gaseous state convert to liquid state ,
Hence , the entropy of the system reduces , i.e. , the randomness decreases .
And the value for entropy is negative ,
hence ,
Δ S = negative ,
Δ H = negative ,
Since ,
The heat is releasing from system .
hence , the most appropriate option will be ΔH and ΔS are negative at all temperatures .
Answer: 11.5 moles of carbon
Explanation:
Based on Avogadro's law:
1 mole of any substance has 6.02 x 10^23 atoms
So, 1 mole of carbon = 6.02 x 10^23 atoms
Z moles = 6.93 x 10^24 atoms
To get the value of Z, cross multiply:
(6.93 x 10^24 atoms x 1mole) = (6.02 x 10^23 atoms x Z moles)
6.93 x 10^24 = (6.02 x 10^23 x Z)
Z = (6.93 x 10^24) ➗ (6.02 x 10^23)
Z = 1.15 x 10
Z = 11.5 moles
Thus, there are 11.5 moles of carbon.
Answer : The correct option is, (C) 1.1
Solution : Given,
Initial moles of
= 1.0 mole
Initial volume of solution = 1.0 L
First we have to calculate the concentration
.


The given equilibrium reaction is,

Initially c 0
At equilibrium

The expression of
will be,
![K_c=\frac{[NO_2]^2}{[N_2O_4]}](https://tex.z-dn.net/?f=K_c%3D%5Cfrac%7B%5BNO_2%5D%5E2%7D%7B%5BN_2O_4%5D%7D)

where,
= degree of dissociation = 40 % = 0.4
Now put all the given values in the above expression, we get:



Therefore, the value of equilibrium constant for this reaction is, 1.1