3. A student obtains the number 0.045006700 on a calculator. If this number actually has four significant figures, how should it be written?
A. 0.4567
B. 0.4501
C. 0.045
D. 0.04500
E. 0.04501

Explanation:

leading zeros do not count as significant figures, Hence, this number correct to four significant figures should be written as in option E.

the electronic configuration of an atom with eight electrons is 1s²2s²2p⁴. the orbital diagrams are shown in the figure.

as per the hunds rule:

1. electrons tend to avoid being in the same orbital as per as practicable.

2. electrons in different orbitals of the same energy will have their spin parallel.

this can be illustrated from the multiplicity of the orbitals of the atom. as there are four electrons in the p orbital and p orbital has 3 sub-shells. the electrons can be fed in different ways as shown in the figure but the correct orbital diagram will be as per the hunds rule.

c. because step up transformer steps up the input voltage i.e increases the input voltage  

the number of turns are greater on the secondary side of step up transformer  

transformer does not handle dc current