Questions

A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment. Such fact-supported theories are not "guesses" but reliable accounts of the real world. Scientific theories are not ever proved in the sense of being proved to be 100% correct.

Examples of some scientific theories are ::

Evolution, gravity, atomic theory, the germ theory of disease, relativity, quantum theory, electromagnetic theory, layered Earth theory, etc...

Infrared spectroscopy involves the interaction of infrared radiation with matter. It is used by chemists to determine functional groups in molecules. IR Spectroscopy measures the vibrations of atoms, and based on this it is possible to determine the functional groups.

Here in the given spectrum, there is no alcohol stretch present in the spectrum. There is no vinyl bending present in the spectrum.
 

Hence, both options B and C are compounds that are not matching with IR spectrum. 1, 5 – Hexadiene is the compound matches the IR Spectrum.

In the given options, "His stomach rumbled like an approaching train" is an example of Simile.

All the other options are examples of metaphors. 

Simile and Metaphor are both figure of speeches in English which are used for comparing things but the only difference is Simile uses LIKE or AS words in comparing and metaphor directly compares without using any words.