NCERT12thchemistrychapter1solutions प्रतिशतता क्या द्रव्यमान प्रतिशत तथा आयतन प्रतिशत#chemisyry12th#chemical #hindimediumchemistry #chemistrybook #motivation #chemestry #chemestry #chemistrybook #motivation #chemistrychapter1 #hindimediumchemistry #chemical #ncertsolutions #ncertchemistryclass12 #ncert12thchemistry solutions