Questions

In chemistry rusting is called as oxidation. Oxidation is a chemical process where metal gains oxygen and become oxide. In rusting the Iron ore make a chemical reaction with the oxygen in the presence of water and environmental or atmospheric moisture to produce an Iron oxide. Iron oxide is otherwise called as rust.

The rusting of iron is a chemical change because it is two substances reacting together to make a new substance. 

Rusting would only be a physical change if iron molecules remained pure iron throughout the process.

All living cells arise from pre-existing cells is one component of the cell theory.

The Cell Theory is one of the basic principles of biology.

The Cell Theory states:

1. All living organisms are composed of cells. They may be unicellular or multicellular.

2. The cell is the basic unit of life.

3. Cells arise from pre-existing cells.

The sentence that states the main idea of the paragraph is called as Thesis or the topic sentence.

The US state California's  economy has surpassed that of the UK to become the world’s fifth largest, according to new federal data released.

With a GDP of $2.7 trillion, California is now only behind the US, China, Japan and Germany.

When the resistance of the air between breaks down the current flows from the positive cloud to the negative cloud in a flash which we call lightning . The difference of potential involves is very high.

New York City, London, and Tokyo are the richest cities in the world 2018, according to their ranks.

Charles Babbage, the father of computer, invented the first general-purpose computer in an effort to prevent the mathematical errors that were prevalent in the human-calculated mathematics of his time.