Questions

Biodegradable substances can be broken down into simpler, harmless substances in nature with due course of time by the biological process such as action of microbes. They can be recycled as a part of food chain.

Here, Leather bags are biodegradable.

Spectrum of an oil frame is an example for continuous emission spectrum

I would do the following if I run out of ideas for a new ad:

       - Word of mouth marketing

       - Direct marketing

       - Public opinions survey

       - Trade show/exhibition promotion etc.  

Application layer protocol defines types of messages exchanged, message format, syntax and semantics and rules for when and how processes send and respond to messages.