Questions

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. 

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

In Britain few of the Canals built during the early days of the Industrial Revolution are now playing an important role in the economy  of the country. Example, Grand Union Canal.

Secondary succession means in an ecosystem renewal of itself after all or a portion has been destroyed.

After a forest fire, the whole forest had destroyed but after that again renewal of that forest is also an example of secondary succession.