<h3>
Answer:</h3>
28.52 seconds
<h3>
Explanation:</h3>
Initial number of atoms of Nitrogen 12,000 atoms
Half-life = 7.13
Number of atoms after decay = 750 atoms
We are required to determine the time taken for the decay.
Note that half life is the time taken for a radioactive isotope to decay to a half of its original amount.
Using the formula;
Remaining amount = Initial amount × (1/2)^n , where n is the number of half lives
In our case;
750 atoms = 12,000 atoms × (1/2)^n
0.0625 = 0.5^n
n = log 0.0625 ÷ log 0.5
n = 4
But, 1 half life =7.13 seconds
Therefore;
Time taken = 7.13 seconds × 4
= 28.52 seconds
Therefore, the time taken for 12,000 atoms of nitrogen to decay to 750 atoms is 28.52 seconds
For 5.43 g/mL and 5.44 g/mL = 0.01 the least diff and most precise.
First of all, precision is determined by the difference in the two obtained values. If the difference between the two values obtained is less, then precision is more. If the difference between the two values obtained is more, then precision is less.
For 5.43 g/mL and 5.44 g/mL , we can see that the difference between these two data is 0.01
For 7.98 g/mL and 7.91 g/mL , we can see that the difference between these two data is 0.07
For 7.65 g/mL and 7.64 g/mL , we can see that the difference between these two data is 0.01
For 7.06 g/mL and 7.03 g/mL , we can see that the difference between these two data is 0.03
As we can see that, the most difference between the data is 0.07 between 7.65 g/mL and 7.64 g/mL and thus, they are least precise.
To know more about precision visit :
brainly.com/question/28336863
#SPJ9
Answer:
D
Explanation:
A The calcium chloride dissolves in solution
B The mass of the solution totals 20 g
C The temperature of the solution is 35 degrees
D The solution became lighter in color
The correct answer would be that <u>the solution became lighter in color.</u>
An increase in temperature can also be considered a sign of a chemical reaction but in this case, the dissolution of calcium chloride in water is in itself exothermic.
A change in the mass of the final solution could also be considered a sign of a chemical reaction but in this case, the total mass equals the addition of the individual masses of the reactant.
The dissolution of calcium chloride in water is not enough as evidence of a chemical reaction. Dissolution can be a physical change of which, the evaporation of the water would retrieve the solute.
<em>A change in color, however, is one of the evidence to establish that a chemical reaction has occurred.</em>
The correct option is D.
brain stem connects the brain to the rest of the body through spinal cord
