Question

Solid NaCl is a bad conductor of electricity because
A. In solid $NaCl$, there are no ions
B. In solid$NaCl$, ions cannot move freely
C. In solid$NaCl$, there are no electrons
D. None of the above.

Answer 1

In solid$NaCl$, ions are bound by strong electrostatic forces. Free ions participate in good electric conduction. When $NaCl$ is dissolved in water, ions are capable of moving and conducting electricity.

Complete step by step answer:
Solid $NaCl$ is a bad conductor of electricity because the charged particles (ions) in solid $NaCl$ are not capable of moving as they are bound by strong electrostatic forces. As a result, they can not conduct electricity. However, water ions are capable of moving when $NaCl$ is dissolved in it and hence conduct electricity.
Now we consider the given options to find the correct answer:
In solid$NaCl$, there are no ions – this statement is wrong because solid NaCl has charged particles i.e ions namely $Na +$and $Cl -$.
In solid$NaCl$, ions cannot move freely – this statement is true because the charged particles (ions) in solid $NaCl$ are not capable of moving as they are bound by strong electrostatic forces. As a result, they can not conduct electricity. So solid$NaCl$ is a bad conductor.
In solid $NaCl$, there are no electrons – this statement is wrong because $NaCl$ has electron that is $Cl^-$
We get the right option from the given options.

So, the correct answer is “Option B”.

Note:
As solid $NaCl$ is a bad conductor, solid $KCl$ is also not a good conductor. Solid $KCl$ is a crystalline solid and the potassium and chlorine atoms are ionically bonded within a crystalline matrix that prevents them from easily moving.
When $NaCl$ is dissolved in water ions $Na^+$ and $Cl^-$ are capable of moving. They become free in the molten state. Hence they can conduct electricity.