Consider the following statements:
a) Both acids and bases change colour of all indicators.
b) If an indicator gives a colour change with an acid, it does not give a change with a base.
c) If an indicator changes colour with a base, it does not change colour with an acid.
d) Change of colour in an acid and a base depends on the type of the indicator.
Which of these statements are correct?
a and d
b and c