Answer:
Option C
Explanation:
∵ Number average molecular mass (M\overline{n})
=\frac{N_{1} M_{1}+N_{2} M_{2}+N_{3} M_{3}}{N_{1}+ N_{2}+N_{3}}
where, N_{1},N_{2} and N_{3} are number of molecules and M_{1} , M_{2} and M_{3} are respectively their molecular masses.
Given
N_{1} = 50 and M_{1} = 5000
N_{2} = 100 and M_{2} = 10000
N_{3} = 50 and M_{3} = 15000
Thus,
M\overline{n}=\frac{N_{1} M_{1}+N_{2} M_{2}+N_{3} M_{3}}{N_{1}+ N_{2}+N_{3}}
=M\overline{n}=\frac{(50 \times 5000) +(100\times 10000)+(50\times 15000)}{50+ 100+50}
= \frac{(25,0000) +(1000000)+(750000)}{200}
M\overline{n}=10,000
Hence, option (c) is the correct answer