Questions

The simplest organic compounds contain only the elements carbon and hydrogen, and are called hydrocarbons.

Here all the given options are hydrocarbons.

The Sunglasses. 

It protects us from the sunlight and it sits on the bridge means hangs on our ears and nose. Only who keeps that can see through it and others wonder what he is watching.

Infrared radiation

A complex sentence is a sentence that contains an independent clause and one or more dependent clauses.

If two clauses are connected with a coordinating conjunction, it's a compound sentence.

If two clauses are connected with a subordinating conjunction, it's a complex sentence.

Tubes that bifurcate from the windpipe are called Bronchi.

The study of flags is called Vexillology and the art of flag design is called as Vexillography. The man who studies flags is called as Vexillologist.