Question

4 g of NaOH is dissolved in 1.0 L solution. The pH of solution is

• A. 13
• B. 1
• C. 12
• D. 7.4

Hint:

For strong bases like NaOH, the concentration of OH\(^-\) is equal to the molarity of the solution.
A quick way to calculate pH for simple concentrations like 0.1 M, 0.01 M, etc., is to first find the pOH, which will be an integer, and then subtract from 14.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
4g NaOH in 1L. Find pH.

Step 2: Key Formula (Alternate):
NaOH is strong base. [OH⁻]=Molarity. pOH=-log[OH⁻]. pH=14-pOH.

Step 3: Detailed Explanation:
Molar mass NaOH=40. Moles=4/40=0.1. [OH⁻]=0.1M. pOH=-log(10⁻¹)=1. pH=14-1=13.

Step 4: Final Answer:
pH is 13.