Because 25% is half of 0.5 and the half life of 
is given as 5,715, the time it takes to reach this amount should just be double the half life: 11430 years.
However, in other cases the problem may not have easy numbers, so below is a more mathematical approach.
The half life formula is 
.
Solving for t gives:
Given information:
Plug in given values and solve for t.
With correct significant figures, this would be 11000 years.
For the answer to the question above,
1∙5µm² = ? m²
1m * 1m = 1m² But 1m = 1,000,000µm = 1x 10^6µm 1x10^6µm * 1x10^6µm = 1m² 1x 10^12µm² = 1m² (Now, try dividing both sides by 1x10^12). 1x10^12µm² /(1x10^12) = 1m² /(1x10^12) 1µm² = 0∙000 000 000 001 m² (multiply both sides by by 1∙5). 1∙5µm² = 0∙000 000 000 0015 m²
1∙5µm² = 1∙5x 10^-12 m²
I hope this helps
I think it is A as solid atoms are close and gases are far away
You need to be able to draw dot-and-cross diagrams to show the ions in some common ionic compounds.
Answer:
Explanation:
1. Calculate the temperature drop
2. Calculate the original temperature
