I am Canadian PR and to maintain PR status person has to be in Canada for two years out of five years. Once I fulfill that requirement and then go out of Canada permanently then will I loose my PR status?

Second question.

If I do not apply for citizenship but my son who is 5 years old can he apply for citizenship?

Any reply on the above would be highly appreciated.

You have answered the first question yourself except for the numbers. Please read the following that is available on the CIC website also
The second part answers your other question about your son. Hope it helps.
Read more on (http://www.cic.gc.ca/english/citizen/index.html)

To become a Canadian citizen you must:

-be 18 years of age or older;
-be a permanent resident of Canada;
-have lived in Canada for at least three of the four years before applying;
-be able to communicate in either English or French;
-know about Canada;
-know about the rights and responsibilities of citizenship;

A child (under 18 years of age) must be a permanent resident of Canada to apply for Canadian citizenship. To apply on behalf of your child you must either:

-already be a citizen; or
-apply for citizenship together as a family.

-----------------------------------------------------------------
wisernow