Answer:
Q = 306 kJ
Explanation:
Given that,
Mass, m = 60 kg
Specific heat, c = 1020 J/kg°C
The temperature changes from 20°C to 25°C.
Let Q be the change in thermal energy. The formula for the heat released is given by :

Put all the values,

So, 306 kJ is the change in thermal energy.
<u>Answer:</u> The time taken by jet plane to reach Los Angeles from Chicago is 3.5 hours
<u>Explanation:</u>
Speed is defined as the rate at which an object moves with respect to time.
To calculate the time taken for the given speed, we use the equation:

where,
s = speed of the jet plane = 800 km/hr
d = distance traveled = 2800 km
t = time taken by jet plane = ?
Putting values in above equation, we get:

Hence, the time taken by jet plane to reach Los Angeles from Chicago is 3.5 hours
Answer : The pH of the solution is, 2.67
Explanation :
The equilibrium chemical reaction is:

Initial conc. 0.450 0 0
At eqm. (0.450-x) x x
As we are given:

The expression for equilibrium constant is:

Now put all the given values in this expression, we get:


The concentration of
= x = 0.00212 M
Now we have to calculate the pH of solution.
![pH=-\log [H^+]](https://tex.z-dn.net/?f=pH%3D-%5Clog%20%5BH%5E%2B%5D)


Therefore, the pH of the solution is, 2.67
Answer:
A. The cost of producing a kilowatt of power with fuel cell will be less than $30 in 2015