What was special about this cities?

The Story Of Harappa|What Was Special About These Cities?|Houses, Drains And Streets|Summary

Write the distribution of electrons in an atom of element whose atomic number is 18. What is special about the outermost electron shell (or valence shell) of the atom of this element ?

what is special about tissue present in the heart?

What is special about tropics that might account for their greater biological diversity ?