Ph scale

Which on is true
A substance with ph is twice as acidic as substance with ph of 4.
A subtances with ph 3 is 10 as acidic as substance with ph of 4.
A substance with ph 3 twice as alkies as substances with ph 4.
a substancs with ph 3 10 time alkies as substance with ph 4.
it was my test question
i don't remember complete sentences.
plz help.

i know about ph scale but still could not undersatand this question .

I can help you determine which statement about the pH scale is true. In the pH scale, which ranges from 0 to 14, a pH of 7 is considered neutral. pH values below 7 are acidic, and pH values above 7 are alkaline or basic.

Now, let's analyze the statements:

Statement 1: "A substance with pH is twice as acidic as a substance with pH of 4."
This statement is not accurate because it does not provide specific pH values. The phrase "pH is" is incomplete, which makes it difficult to determine the accuracy of the statement.

Statement 2: "A substance with pH 3 is 10 times as acidic as a substance with pH of 4."
This statement is true. According to the pH scale, each decrease in pH value by one unit indicates a tenfold increase in acidity. Therefore, a substance with a pH of 3 is 10 times as acidic as a substance with a pH of 4.

Statement 3: "A substance with pH 3 is twice as alkali as a substance with pH 4."
This statement is not correct. pH values below 7 indicate acidity, not alkalinity. Therefore, a substance with a pH of 3 would be acidic, not alkaline.

Statement 4: "A substance with pH 3 is 10 times as alkali as a substance with pH 4."
This statement is also inaccurate. Like the previous statement, it suggests alkalinity for a pH value of 3, which is incorrect.

Based on the information provided, we can conclude that statement 2 is true: "A substance with pH 3 is 10 times as acidic as a substance with pH of 4."