Answer:
81°C.
Explanation:
To solve this problem, we can use the relation:
<em>Q = m.c.ΔT,</em>
where, Q is the amount of heat released from water (Q = - 1200 J).
m is the mass of the water (m = 20.0 g).
c is the specific heat capacity of water (c of water = 4.186 J/g.°C).
ΔT is the difference between the initial and final temperature (ΔT = final T - initial T = final T - 95.0°C).
∵ Q = m.c.ΔT
∴ (- 1200 J) = (20.0 g)(4.186 J/g.°C)(final T - 95.0°C ).
(- 1200 J) = 83.72 final T - 7953.
∴ final T = (- 1200 J + 7953)/83.72 = 80.67°C ≅ 81.0°C.
<em>So, the right choice is: 81°C.</em>
Answer:

Explanation:
pH is derived from the concentration of hydronium ions in a solution. Hydrocyanic acid is HCN.
First, we shall figure out the moles of HCN:

If HCN was a strong acid:
HCN has a 1:1 ratio of H+ ions, the moles of H+ is also the same.
To find the molarity, we now divide by Liters. This gets us:

Finally, we plug it into the definition of pH:
![pH = -log[H^{+} ]](https://tex.z-dn.net/?f=pH%20%3D%20-log%5BH%5E%7B%2B%7D%20%5D)


However, since HCN is a weak acid, it only partially dissociates. The
of HCN is
.
![K_a = \frac{[H^+][A^-]}{[HA]}](https://tex.z-dn.net/?f=K_a%20%3D%20%5Cfrac%7B%5BH%5E%2B%5D%5BA%5E-%5D%7D%7B%5BHA%5D%7D)
We can use an ice table to determine that when x = H+,

![[H^+] = 8.83*10^{-6}](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%20%3D%208.83%2A10%5E%7B-6%7D)
![pH = -log[H^{+} ]](https://tex.z-dn.net/?f=pH%20%3D%20-log%5BH%5E%7B%2B%7D%20%5D)


Answer: The final temperature would be 1250.7 K.
Explanation: We are given a sample of helium gas, the initial conditions are:
(Conversion factor: 1L = 1000 mL)
(Conversion Factor: 1° C = 273 K)
The same gas is expanded at constant pressure, so the final conditions are:


To calculate the final temperature, we use Charles law, which states that the volume of the gas is directly proportional to the temperature at constant pressure.


Putting the values, in above equation, we get:


Gaseous
The atoms are taking up the volume of the entire container
I think it’s called Gaseous state or water vapor