Which pair below describes isotopes of the same element?
a) an atom with 6 protons and 8 neutrons - an atom with 8 protons and 6 neutrons
b) an atom with 6 protons and 6 neutrons - an atom with 6 protons and 7 neutrons
c) an atom with 8 protons and 8 neutrons - an atom with 7 protons and 8 neutrons
d) an atom with 7 protons and 6 neutrons - an atom with 6 protons and 6 neutrons
8)

B

Explanation:

For exhibit isotopy, atoms of the element must have the same proton number (atomic number) but different mass number.

In Option B

The two atoms have same atomic number (6) but different mass number (12 and 13 respectively).

Mass num = proton number + Neutron number

Unlike the other options.

the electrical  conductivity  of asolution  of an electrolyte is measured by determining the resistance of thesolution  between two flat or cylindrical electrodes separated by a fixed distance.

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.