Discussion
A gas is 40 mole per cent methane of molar mass 16 and 60 mole per cent ethane of molar mass 30. What is its average molar mass?
Answer: D
Correct answer: 24.4
The average molar mass is the mole-fraction-weighted mean: \[ 0.4\times16 + 0.6\times30 = 6.4 + 18 = 24.4. \] Because the weights are *mole* fractions the answer must lie between 16 and 30 and nearer the ethane, which is what the 60 per cent implies - and the 23.0 offered is the unweighted average of the two, which would be right only for an equimolar mixture.
No comment is present. Be the first to comment.
Loading…
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development