What are the disadvantages of Algol programming language?

The disadvantage is poor reliability due to the ease with which type errors can be made, coupled with the impossibility of type checking detecting them

I assume the major disadvantage is due to the lack of popularity.

"c is a mother language no dis advantage." If there were no disadvantages to C, then C would be the only programming language! C is not an object oriented language - to make it so, C++ was developed....

You have to plan the structure of your program, as you cannot just goto anywhere, as you could in an unstructured language (like BASIC or Assembly).