Questions

A pure solid and a pure liquid are definitely a single phase because they are so united, or homogeneous. This leads to a homogeneous mixture also being a single phase.

Hence, the option that cannot be considered a single phase is A. a heterogeneous mixture.

I am black gold i.e charcoal. It is black when it is not used and when using it is red due to fire and when used it is in grey color as it becomes ash. 

A data structure is a specialized format for organizing and storing data. General data structure types include the array, the file, the record, the table, the tree, and so on. Any data structure is designed to organize data to suit a specific purpose so that it can be accessed and worked with in appropriate ways.

Linear data structure: A linear data structure traverses the data elements sequentially, in which only one data element can directly be reached.

Ex: Arrays, Linked Lists, Stack, Queue, Any type of List all are linear.

Trees like Binary Tree, B Tree or B+ Tree are examples of non linear data structure.

Light travels fastest in Vacuum. The fastest thing in the whole universe is the speed of light in a vacuum like outer space. It is about 2.99 x 10⁸ m/s. 

Crime connected with illegal alcohol production and sale became a major issue so that even many people who had originally supported Prohibition decided that it needed to be repealed.

Maps.