Answer:
All the options are correct except "has 7 electrons"
Step-by-step explanation:
When two or more elements have the same atomic number (with a particular element in the periodic table) but different mass numbers (with that element), these elements are said to exhibit isotopy. Hence, isotopy is a phenomenon in which different elements have the same atomic number but different mass number. These elements are referred to as isotopes of the element in the periodic table.
Isotopes of a particular element have the same atomic number which means they have the same number of protons (and also electrons since number of protons is usually equal to the number of electrons except there is a charge). Because they have the same number of electrons, they still have the same number of electron shells as the main element and are assumed to be in the group of the main element. These isotopes have different mass number and hence have different number of neutrons (because, mass number = atomic number + number of neutrons).
From the explanation above, it can be deduced that carbon-13 is an isotope of carbon-12. Carbon-13 has two electron shells just like carbon-12. Carbon-13 can also be assumed to be a member of period 2 since carbon-12 is a member.
However, carbon-13 has different number of neutrons with carbon-12 since the mass numbers are different.
Where the atomic number of carbon-13 is 6 and it's mass number is 13
number of neutrons = mass number - atomic number
number of neutrons = 13 - 6 = 7
Since the atomic number of carbon-13 is 6, its number of electrons is also 6 not 7.
Hence, all the options are correct except "has 7 electrons"