Questions

 4600 million

Amazon Rainforest Forests are located in South America.

We know that, elements in the same group of the periodic table have similar characteristics. Here magnesium and strontium are the same 2nd group elements and have same behavior. 

Therefore, strontium behaves same as magnesium. 

Most organic compounds contain carbon and hydrogen.

Microscopes are of three types. They are :

1) Optical microscopes

2) Electron microscopes

3) Scanning tunneling microscopes

Scanning tunneling microscopes are the microscopes that are used to view metal surfaces.

Urea is a by product of amino acid catabolism, Which occurs in the liver. The nitrogen in the  amino acid becomes converted to ammonia and this is further converted by the liver into urea