Question

क्या है जो साफ रहने पर काला होता है, लेकिन जब गन्दा होता है तो सफ़ेद होता है

Answer 1

Answer:

blackboard

Explanation:

the colour of blackboard is black so when it's clean it colour is black and we write on it with chalk .So,when it is dirty it's colour is white