Zumdahl solidstate marathon

First of all I apologise to sir that I m currently out station so can't solve questions...but like in this question I wanted to know ki first wale se kch khaas vaisa result nhin nikla but in the second one partial fraction se density compare krke jo total density ayega usse volume of an atom se multiply krke M ka mass aa jayega n...similarly done with anion...and then we will get back to the step a wala equation...I ain't sure if I m going the right way #💭│doubts #🧪│chem-questions #zumdahl