Turmeric is a natural indicator which can be used to test whether a given substance is acidic or basic in nature.
When we put drops of alkaline solution like NaOH or NaHCO3 solution on turmeric paper, It turns to brownish red in colour indicating the nature of solution as basic.
When an acid is poured on turmeric paper, there will not be any effect.
Conclusion :
Turmeric paper + acid = No change in colour
Turmeric paper + base= brownish red colour.