Sometimes it is difficult to recognize a voice over telephone,why?

Why is it difficult to walk on ice ?

Why is the extraction of copper from pyrites more difficult than that from its oxide ore through reduction?

Why has it been difficult to study the chemistry of radon?

Explain, why is it difficult for a fireman to hold a hose, which ejects large amounts of water at a high velocity.

Why is an insulator sometimes called a dielectric? What is the main difference between free and bound charge? Generally one of the two plates of a Capacitor System is earthed, why? Derive the expression for the energy stored in a charged capacitor.

Why is it difficult to hold a school bag having a strap made of a thin and strong string?

Why are the symptoms of toxicity difficult to identify?

Why does oil form a thin film over the surface of water?