The atomic number of iron, Fe, is 26. This means it has 26 electrons.
Now, as we write the configuration, we come up to electronic subshell 3p, which is completely filled. So the configuration up till this point is identical to Argon, so we may write:
[Ar], 3d, 4s
After the electrons in the Ar configuration are accommodated, there are 8 electrons left for the 3d and 4s shells. The 4s subshell, when empty, is at a lower level than the 3d level, so it fills first. Two electrons are placed here. Therefore, 3d has 6 electrons in Fe.
Answer:
A. To be precise, it must be able to make measurements repeatedly over a long period of time.
Explanation:
The precision of a scientific measuring tool can be defined as how close the values between multiple measurements are to each other, when repeated under the same conditions.
This ultimately implies that, the precision of a scientific measuring tool reflects the reproducibility and repeatability of its measurements, irrespective of how accurate the measurements are.
In science, one of the most effective ways to determine the precision of a scientific measuring tool is to find the difference between the highest and lowest measurements (measured values).
Hence, the statement which correctly describes a characteristic that a scientific measuring tool should have is that, to be precise, it must be able to make measurements repeatedly over a long period of time.
-delta H symbolises an exothermic reaction. Hence, it gives off heat. Reversely, it would absorb heat.
A reaction that is spontaneous means that it can produce products without the supply of energy. The total energy from the reactants reached the activation energy that allow the reaction proceed. An example of this is the decay of a diamond into graphite occuring readily.
