<em><u>because if any metals are there in the flour it would attract it...</u></em>
<em><u>hope it helps you</u></em>
<em><u>and mark as best answer please</u></em>
Complete Question
The complete question is shown on the first uploaded image
Answer:
a

b

Explanation:
From the question we are told that
The image distance is 
The value of the image is negative because it is on the same side with the corrective glasses
The object distance is 
The reason object distance is because the object father than it being picture by the eye
General focal length is mathematically represented as

substituting values

=> 
Generally the power of the corrective lens is mathematically represented as

substituting values


Answer:
+16 J
Explanation:
We can solve the problem by using the 1st law of thermodynamics:

where
is the change of the internal energy of the system
Q is the heat (positive if supplied to the system, negative if dissipated by the system)
W is the work done (positive if done by the system, negative if done by the surroundings on the system)
In this case we have:
Q = -12 J is the heat dissipated by the system
W = -28 J is the work done ON the system
Substituting into the equation, we find the change in internal energy of the system:
