Answer: -
37.5 g of NaCl are in 250 g of a 15.0% (by weight) solution.
Explanation: -
Total mass = 250 g
Percentage of NaCl = 15.0 %
= 
Thus
= 
Number of grams of NaCl present = 
= 37.5 g
When two plates push against each other shear stress will happem because they move in opposite directions. In this case the force of the stress pushes some of the crust in different directions. When this happens, a large part of the crust can break off, which makes the plate size smaller.
Answer:
Metal
Element: Calcium
Valency: 2
Explanation:
To find the element, let's use the periodic table. (Look below)
We already went past 3 shells, just need the 2 electrons after it.
Just skip to the 4th row and count 2 to the right
We end up at Calcium.
Calcium is a metal and we're also on the alkaline earth metals column.
Calcium will need to lose 2 electrons to reach stability, so the valency is 2.