4. Take a beaker with some water and place a lighted candle in standing position in it. Now cover the candle with a test tube to cut off it air supply. For how long does the candle keep on burning? How much water rises up in the test tube? Why did it happen so? Explain with diagram. You can perform this experiment with utensils available at your home in case of non availability of the beaker and test tube.

answer: option (a) is the correct answer.

explanation:

the measurement of hydrogen ions in a solution is known as ph.

if ph of a solution is less than 7 then the solution is acidic. if ph of a solution is greater than 7 then the solution is basic.

when the ph of a solution equals 7, then the solution is considered as neutral.

the ph of pure water is 7, therefore, it means that concentration of hydronium ions equals that of hydroxide ions.