Questions

We know that, Elements in the same group of the periodic table have similar characteristics.

Here Magnesium and Strontium shared some similar properties because they both belong to the same group. Sr is the chemical symbol for strontium which is a group two element; it has atomic number of 38. 

The first central legislative assembly constituted in the year 1920.

72% of the totally emitted greenhouse gases is carbon dioxide.

Hence, Carbon dioxide (Co2) is predominantly responsible for Global warming.

Southern Democrats are members of the U.S. Democratic Party who reside in the South. All the above given were the part of agenda of southern democrats.

Using fear and violence for political gain is the part of the agenda of southern democrats most directly affected African American.

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...