Questions

Exercise is a subset of physical activity that is planned, structured and repetative.

A rift valley is an elongated trough like feature bounded by faults. The term 'garben' is considered synonymous to rift valley.

The most important polymer present in the nucleus is DNA- the master molecule. It is a polymer of Nucleotides.

Because V K Krishna Menon spoke for 13hours continuously while representing india.

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.