Answer:
mole = mass / Mr.
mass = 9.8g
Mr. of NaCl = 23 + 35.5 = 58.5
Mole = 9.8/ 58.5 = 0.168 moles
Answer:
Z= 1.96
Explanation:
The Z score that corresponds to 95% is 1.96.
Medicine i think but im not positive
Answer:
1990 and 2010

Explanation:
Let:

We need to know, in what year(s) the villages had the same population, mathematically this is:

So:

Solving for x:
Factoring

Hence:

Therefore the year(s) which the village had the same population are:

In order to find the population of both cities during the year(s) of equal population, just evalue the equations at x=15 and x=35:
