Plaque is a deposit which collects around teeth. The following table shows the pH value of the plaque surrounding the teeth of a girl over 4 hrs.
(i) Other than food remains, state three constituents of plaque.
(ii) State the time during the day when condition are most favourable for the process of tooth decay.
(i) The three constituents of plaque other than food are acid, saliva and bacteria.
(ii) Time 4 has the lowest pH, which indicates the highest amount of acid produced by the bacteria.