question_answer

                    Following table shows the pH value of the plaque surrounding the teeth of a girl over 3 hrs. Plaque is a deposit which collects around teeth.

Time/h	pH
0.0	7.0
01.0	7.0
02.0	7.1
03.0	7.2
0.40	4.1

(a) Other than food remains, state three    constituents of plaque.                  (b) State the time during the day when   condition most favourable for process  of tooth decay.

Answer:

                    (a) The three constituents of plaque other than  food are acid, saliva and bacteria.      (1) (b) Time 4.0, lowest pH indicate the highest  amount of acid produced by the bacteria.   (1)