Which of the following statements is/are correct?

I. Salts of a strong acid and weak base are acidic with pH value less than 7.

II. When electricity is passed through an aqueous solution of sodium chloride (called brine), it decomposes to form sodium oxide.

Only I

The correct answer is option 4. Only I.

Let us break down each statement:

I. Salts of a strong acid and weak base are acidic with pH value less than 7:

True: Salts formed from the reaction of a strong acid and a weak base will have acidic properties. This is because the anion from the weak base can hydrolyze in water, leading to the formation of acidic solutions. So, the pH value will be less than 7.

II. When electricity is passed through an aqueous solution of sodium chloride (called brine), it decomposes to form sodium oxide:

False:  When electricity is passed through brine (sodium chloride solution), a process called electrolysis occurs. This process results in the decomposition of sodium chloride (NaCl) into sodium ions (Na⁺) and chloride ions (Cl⁻), but it does not form sodium oxide. The products are typically sodium hydroxide (NaOH) at the cathode and chlorine gas (Cl₂) at the anode.

Therefore, the correct option is 4. Only I.