Answer:
Valence electrons. they can be used to determine the group of an element.
Explanation:
Answer:
The efficiency rating of the jack is 0.067.
Explanation:
We have, a person applies a force of 200 N over 1.5 m to a jack. The jack exerts a 1000-N force on a car a distance of 0.02 m.
It is required to find the the efficiency rating of the jack. It is equal to the ratio of output work to the ratio of input work. So,

Thus, the efficiency rating of the jack is 0.067.
Answer:
15.7g
Explanation:
mass percent=mass of element/mass of compound *100
39.34=unknown(x)/40g×100
39.34=5x/2
multiplying both sides by 2,we get
5x=78.68
devide by 5 on both sides
x=15.74g Na