Edge effect' is observed in case of

The peroxide effect is observed in case of HBr and not with HF, HCl or HI. Give reason.

Assertion : Doppler effect is not observed in case of supersonic waves. Reason : Waves produced by supersonic sources are shock waves which produce a sound.

Photo electric effect is not observed in case of

Tyndall effect is observed in

Screening effect is not observed in :

Screening effect is not observed in :

Tyndell effect is observed when