Answer: 502 Joules
Explanation:
To calculate the mass of water, we use the equation:

Density of water = 1 g/mL
Volume of water = 40.0 mL
Putting values in above equation, we get:

When metal is dipped in water, the amount of heat released by lead will be equal to the amount of heat absorbed by water.

The equation used to calculate heat released or absorbed follows:

q = heat absorbed by water
= mass of water = 40.0 g
= final temperature of water = 20.0°C
= initial temperature of water = 17.0°C
= specific heat of water= 4.186 J/g°C
Putting values in equation 1, we get:
![q=40.0\times 4.186\times (20.0-17.0)]](https://tex.z-dn.net/?f=q%3D40.0%5Ctimes%204.186%5Ctimes%20%2820.0-17.0%29%5D)

Hence, the joules of heat were re-leased by the lead is 502
So for D you have to find energy right
from c you get wavelength Lambda
so on D use this
E = Hc / lambda
c is given 1.5 x 10 ^20
h = 6.624 x 10^-34
and then you get answer for energy
The first reason to repeat experiments is simply to verify results. Different science disciplines have different criteria for determining what good results are. Biological assays, for example must be done in at least triplicate to generate acceptable data. Science is built on the assumption that published experimental protocols are repeatable.
2) The next reason to repeat experiments is to develop skills necessary to extend established methods and develop new experiments. “Practice make perfect” is true for the concert hall and the chemical laboratory.
3) Refining experimental observations is another reason to repeat. Maybe you did not follow the progress of the reaction like you should have.
4) Another reason to repeat experiments is to study and/or improve them in way. In the synthetic chemistry laboratory, for example, there is always a desire to improve the yield of a synthetic step. Will certain changes in the experimental conditions lead to a better yield? The only way to find out is to try it! The scientific method informs us that it is best to only make one change at a time.
5) The final reason to repeat an extraction, chromatographic or synthetic protocol is to produce more of your target substance. This is sometimes referred to scale-up.
<u><em>Answer:</em></u>



<u><em>Explanation:</em></u>
<u>Part 1: Solving for m</u>
<u>We are given that:</u>
E = mc²
To solve for m, we will need to isolate the m on one side of the equation
This means that we will simply divide both sides by c²

<u>Part 2: Solving for c</u>
<u>We are given that:</u>
E = mc²
To solve for c, we will need to isolate the m on one side of the equation
This means that first we will divide both sides by m and then take square root for both sides to get the value of c

<u>Part 3: Solving for E</u>
<u>We are given that:</u>
m = 80 and c = 0.4
<u>To get the value of E, we will simply substitute in the given equation: </u>
E = mc²
E = (80) × (0.4)²
E = 12.8 J
Hope this helps :)