The isotopes half life is 2 hours
Since given the following :
time = 8 hours × 3600s/hr = 28800 seconds
A₀ = 80 Bq as the first registration of detector counts per second
A = 5 Bq as the registration of detector counts per second eight hours later
Using the formula:
∴ A = A₀ e^-λt
∴ A/A₀ = e^-λt
∴ ln (A/A₀) = -λt
∴ λ = -ln (A/A₀) /t = ln2 / t_{1/2}
∴ t_{1/2} = -ln2 / ln(A/A₀) (t)
∴ t_{1/2} = -ln2 / ln(5/80) (8 hours) = 2 hours
Here we have to add the two measurements given in the question
The measurement values are given as 1.0090 cm and 0.02 cm.we have to add them on the basis of significant figure rules.
As per the addition rule in terms of significant figures
1-First we have to select the number of significant digits after the decimal point of each quantity.
2-Now we have to remember that during the addition ,the resultant of two quantities will follow the quantity having least number of significant figures after the decimal point.
3-Here we are considering the minimum number of significant figures after the decimal points not the minimum number of significant figures in case of multiplication and division
Now we have to add these two quantities as per the above rule-
1.0090 cm +0.02 cm
=1.0290 cm
Here the result will follow 0.02 which has minimum number of significant figures after the decimal points.
Hence we have to round off the number from 9 of 1.0290
As 9 is greater than 5 ,so he actual result will be 1.03 cm
A is not linked. Coal burning is not an effect of acid rain.
~Deceptiøn
Answer:
The second vector 
points due West with a magnitude of 600N
Explanation:
The original vector 
points with a magnitude of 200N due east, the Resultant vector 
points due west (that's how east/west direction can be interpreted, from east to west) with a magnitude of 400N. If we choose East as the positive direction and West as the negative one, we can write the following vectorial equation:
With the negative sign signifying that the vector points west.
