The following substances can not distinguish dilute hydrochloric acid from sodium hydroxide solution: A purple litmus B colorless phenolphthalein C sodium chloride solution D zinc particles

The following substances can not distinguish dilute hydrochloric acid from sodium hydroxide solution: A purple litmus B colorless phenolphthalein C sodium chloride solution D zinc particles

Answer C
A Purple litmus makes acid red and alkali blue
B Phenolphthalein turns red with alkali
DZn can react with acid to form bubbles

What happens if you have a bottle of sodium hydroxide solution and add the same amount of litmus test solution and phenolphthalein? Litmus test solution and phenolphthalein were added simultaneously. What happens if you have a bottle of sodium hydroxide solution and add the same amount of litmus test solution and phenolphthalein? Litmus test solution and phenolphthalein were added simultaneously.

That's a special question.
But to be exact, you have to look at the pH of NaOH.
Because:
The color of litmus varies from pH 5.0 to 8.0.
Phenolphthalein is a weak organic acid with red quinone structure at pH <8.2的溶液里为无色的内酯式结构,当pH>8.2.
But due to the different conditions of the reaction, it can be regarded as color change from PH =8.
Therefore:
1. When PH=8, the phenolphthalein will turn red when it is mixed with dilute solution of sodium hydroxide, and the stamen and phenolphthalein will not react with each other.