"Work done by a constant force on an object is the product of the force and the distance moved by the object in the direction of the force" -textbook
There is work done ONLY if the direction of the force and the direction the item is moving are the same. In figure A, the direction of the force (the lifting) is upwards (defying gravity), and the book is moving upwards, so work is done. In figure B, the force is still moving upwards (the person is carrying the books) but the book is moving to the right, so there is NO work done.
Answer:

Explanation:
Hello there!
In this case, according to the given chemical reaction whereas the sodium chloride is in a 2:1 mole ratio with chlorine, the required moles of the later are computed as shown below:

So we cancel out the moles of NaCl to obtain:

Best regards!
Answer:
2.61
Explanation:
pH+pOH=14, so sub in 11.39 for pOH, then subtract it over to get pH=2.61
if you have any questions, leave them in the comments and i will try to answer them, if this helped, pls give brainliest.