Questions

Muhammad had to leave Mecca his birth place where he started preaching and take refuse in Medina, where he was given a warm welcome. This event took place in AD 622 and is known as the year of the Hijira, or migration, which became the first year of the Muslim Calendar.

The USSR( now a Common Wealth of Independent States) is spread over Europe and Asia

Madhya Pradesh has won the 'Best Tourism State' national award for the third consecutive year. President Ram Nath Kovind handed over the award, named as 'Hall of Fame Award', to Minister of State for Tourism Surendra Patwa at a ceremony held at Vigyan Bhawan in New Delhi.

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

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.

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