Explain two reasons why SI is easier to use than the English system
2 answers:
Answer:
1. SI units are easy to remember
2. English system needs lots of calculation while converting it from one unit to other
3. SI unit is universally accepted.
Explanation:
1. SI units are easy to remember
2. English system needs lots of calculation while converting it from one unit to other.
in SI unit base 10 is used to convert from one unit to other,I is similar to number system, therefore it is very easy to remember and convert between units.
In English system it is very difficult to memorize when we have to convert bigger unit to smaller unit by several orders of magnitude and it needs lots of calculation.
Example:
Suppose we have to determine how many millimeters are there in a meter? then we can easily determine
we can easily remember it as milimeter means
on the other hand if we have convert microns into a mile than it needs lots of calculation.
3. SI unit is universally accepted.
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Explanation:
According to the Beer-lambert' s law,
Absrobance = absrobptitvity × lenght × concentration
So, if we will plot a graph between absrobance and concentration then we will obtain a straight line
Hence, formula to calculate slope of the graph is as follows.
The slope of graph =
The given data is as follows.
= 0.412 (first point)
= 0.642 (second point)
= 0.240 ppm (first point)
= 0.475 ppm (second point)
Hence, putting these values into the above formula we will calculate the value of slope as follows.
Slope =
=
=
= 0.978
It is known that for the graph, line equation can be written as follows.
y = mx + c ........... (1)
where, C = intercept
m = slope
Hence, calculate the value of intercept as follows.
0.412 = + c
c = 0.178
As it is given that the absorbance values 0.454 (the y-axis value). Therefore, putting this value into equation (1) we get the following.
y = mx + c
0.454 = + 0.178
0.276 = 0.978x
x = 0.282 ppm
Thus, we can conclude that the concentration of Pb in the given sample is 0.282 ppm.