Step 1: Understanding the Question:
The question asks to identify a weak electrolyte from the given list of chemical compounds.
An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvent, such as water.
The classification into strong and weak electrolytes depends on the degree of ionization or dissociation in solution.
Step 2: Detailed Explanation:
Electrolytes and Ionization:
Electrolytes are substances that dissociate into free ions in solution, allowing the liquid to conduct electricity.
Strong electrolytes are those that dissociate almost completely (\(\approx 100%\)) into ions. This group includes strong acids, strong bases, and most soluble salts.
Weak electrolytes are substances that only partially dissociate in water. In their solutions, a dynamic equilibrium exists between the un-ionized molecules and the ions produced.
Analysis of the Options:
1. \(H_2SO_4\) (Sulphuric Acid): It is a strong mineral acid. In aqueous solution, it dissociates completely into \(H^+\) and \(SO_4^{2-}\) ions. Therefore, it is a strong electrolyte.
2. \(NaOH\) (Sodium Hydroxide): It is a strong base. Being an ionic solid, it dissociates completely into \(Na^+\) and \(OH^-\) ions upon dissolution in water. Thus, it is a strong electrolyte.
3. \(NaCl\) (Sodium Chloride): It is a typical salt formed from a strong acid and a strong base. It exists as an ionic lattice that breaks down completely in water to yield \(Na^+\) and \(Cl^-\) ions, making it a strong electrolyte.
4. \(H_2CO_3\) (Carbonic Acid): It is a weak diprotic acid. When dissolved in water, it only partially ionizes into \(H^+\) and \(HCO_3^-\) ions. The reaction is reversible: \(H_2CO_3 \rightleftharpoons H^+ + HCO_3^-\). Because only a small fraction of molecules ionize at any given time, it is classified as a weak electrolyte.
Step 3: Final Answer:
Among the given options, \(H_2CO_3\) (Carbonic Acid) is the only weak electrolyte as it undergoes partial ionization in aqueous solution.