Răspuns:
se foloseste relatia c=mdx100/ms= mdx100/(md+m,apa)
1.
12= mdx100/40---> md= 4,8g
m,apa= ms-md= 40g-4,8g= 35,2g
2
30= 120x100/(120+m,apa)
30x120+ 30m,alpa= 12000
m,apa= 280g
3. 15= mdx100/(md+68)
calculeaza md !!!
4. md= ms-m,apa= 480g-450g= 30g
c= 30x100/480=......calculeaza !!
5. Explicație: