Question

answer all the question No spam!!​

Answer 1

1. The reaction taking place here is the precipitation reaction. Sulphur is solid, it turns the solution cloudy.
2. The cross mark disappears due to cloudiness. As this is a precipitation reaction, the solution becomes cloudy and soon the cross mark disappears.
3. (NH4)2Cr2O7→Cr2O3+N2+4H2O(4.1.2)

I am not sure about my answer..