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
Mean: the average. you have to add the values of the numbers and then divide by the amount of numbers there are. a common mistake to avoid is forgetting to divide the numbers at the end or subtracting them instead of adding.
mean: the middle number. you would first need to order the numbers from least to greatest. a common mistake to avoid is finding the middle number before ordering it from least to greatest
these two can also be commonly mistaken for one another because of the similar spelling.
b. o2
oxygen is diatomic because 1 molecule is made of 2 atoms of oxygen
The oxidation half reaction of the reaction given above would be: Ca → Ca + 2e−. Oxidation is the loss of electrons of an element while its counterpart is called the reduction which gains the electrons that has been lost. Hope this answers the question.
