JEE Exam  >  JEE Questions  >  Two elements A and B form compounds AB2 and A... Start Learning for Free
 Two elements A and B form compounds AB2 and AB4 (both are non-volatile and non-electrolyte) when dissolved in 20.0 g benzene, 1 g of AB2 lowers the freezing point of benzene by 2.3 K, whereas 1.0 g of AB4 lowers it by 1.3 K [Kf (benzene) = 5.5 K mol-1 kg]. ; Thus, atomic masses of A and B respectively, ar
  • a)
    120,212
  • b)
    96,28
  • c)
    212,120
  • d)
    28,46
Correct answer is option 'D'. Can you explain this answer?
Verified Answer
Two elements A and B form compounds AB2 and AB4 (both are non-volatile...
w1/m1= moles of solute in w2 g solvent
A+2B =120                       ...(i)
A+4B = 212                   ...(2)
On solving Eqs. (i) and (Hi), we get
∴       B = 46 
           A = 28
View all questions of this test
Most Upvoted Answer
Two elements A and B form compounds AB2 and AB4 (both are non-volatile...
Given Data:
- Mass of benzene (molar mass = 78.1 g/mol) = 20.0 g
- Kf (freezing point depression constant of benzene) = 5.5 K mol-1 kg
- Freezing point depression caused by 1 g of AB2 = 2.3 K
- Freezing point depression caused by 1 g of AB4 = 1.3 K

Calculations:
Let the molar mass of A be x and the molar mass of B be y.
For AB2:
- Moles of AB2 = 1g / (x + 2y)
- Molality of AB2 = (1 g / (x + 2y)) / 0.020 kg = 50 / (x + 2y) mol/kg
- Freezing point depression caused by AB2 = Kf * molality of AB2 = 5.5 * 50 / (x + 2y) K
- Given that the depression is 2.3 K, we have: 5.5 * 50 / (x + 2y) = 2.3
For AB4:
- Moles of AB4 = 1g / (x + 4y)
- Molality of AB4 = (1 g / (x + 4y)) / 0.020 kg = 50 / (x + 4y) mol/kg
- Freezing point depression caused by AB4 = Kf * molality of AB4 = 5.5 * 50 / (x + 4y) K
- Given that the depression is 1.3 K, we have: 5.5 * 50 / (x + 4y) = 1.3
Solving the above two equations simultaneously will give the values of x and y.

Final Answer:
After solving the equations, we find that the molar mass of A is 28 and the molar mass of B is 46. Therefore, the correct option is D (28, 46).
Explore Courses for JEE exam
Two elements A and B form compounds AB2 and AB4 (both are non-volatile and non-electrolyte) when dissolved in 20.0 g benzene, 1 g of AB2 lowers the freezing point of benzene by 2.3 K, whereas 1.0 g of AB4 lowers it by 1.3 K [Kf (benzene) = 5.5 K mol-1 kg]. ; Thus, atomic masses of A and B respectively, ara)120,212b)96,28c)212,120d)28,46Correct answer is option 'D'. Can you explain this answer?
Question Description
Two elements A and B form compounds AB2 and AB4 (both are non-volatile and non-electrolyte) when dissolved in 20.0 g benzene, 1 g of AB2 lowers the freezing point of benzene by 2.3 K, whereas 1.0 g of AB4 lowers it by 1.3 K [Kf (benzene) = 5.5 K mol-1 kg]. ; Thus, atomic masses of A and B respectively, ara)120,212b)96,28c)212,120d)28,46Correct answer is option 'D'. Can you explain this answer? for JEE 2024 is part of JEE preparation. The Question and answers have been prepared according to the JEE exam syllabus. Information about Two elements A and B form compounds AB2 and AB4 (both are non-volatile and non-electrolyte) when dissolved in 20.0 g benzene, 1 g of AB2 lowers the freezing point of benzene by 2.3 K, whereas 1.0 g of AB4 lowers it by 1.3 K [Kf (benzene) = 5.5 K mol-1 kg]. ; Thus, atomic masses of A and B respectively, ara)120,212b)96,28c)212,120d)28,46Correct answer is option 'D'. Can you explain this answer? covers all topics & solutions for JEE 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Two elements A and B form compounds AB2 and AB4 (both are non-volatile and non-electrolyte) when dissolved in 20.0 g benzene, 1 g of AB2 lowers the freezing point of benzene by 2.3 K, whereas 1.0 g of AB4 lowers it by 1.3 K [Kf (benzene) = 5.5 K mol-1 kg]. ; Thus, atomic masses of A and B respectively, ara)120,212b)96,28c)212,120d)28,46Correct answer is option 'D'. Can you explain this answer?.
Solutions for Two elements A and B form compounds AB2 and AB4 (both are non-volatile and non-electrolyte) when dissolved in 20.0 g benzene, 1 g of AB2 lowers the freezing point of benzene by 2.3 K, whereas 1.0 g of AB4 lowers it by 1.3 K [Kf (benzene) = 5.5 K mol-1 kg]. ; Thus, atomic masses of A and B respectively, ara)120,212b)96,28c)212,120d)28,46Correct answer is option 'D'. Can you explain this answer? in English & in Hindi are available as part of our courses for JEE. Download more important topics, notes, lectures and mock test series for JEE Exam by signing up for free.
Here you can find the meaning of Two elements A and B form compounds AB2 and AB4 (both are non-volatile and non-electrolyte) when dissolved in 20.0 g benzene, 1 g of AB2 lowers the freezing point of benzene by 2.3 K, whereas 1.0 g of AB4 lowers it by 1.3 K [Kf (benzene) = 5.5 K mol-1 kg]. ; Thus, atomic masses of A and B respectively, ara)120,212b)96,28c)212,120d)28,46Correct answer is option 'D'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of Two elements A and B form compounds AB2 and AB4 (both are non-volatile and non-electrolyte) when dissolved in 20.0 g benzene, 1 g of AB2 lowers the freezing point of benzene by 2.3 K, whereas 1.0 g of AB4 lowers it by 1.3 K [Kf (benzene) = 5.5 K mol-1 kg]. ; Thus, atomic masses of A and B respectively, ara)120,212b)96,28c)212,120d)28,46Correct answer is option 'D'. Can you explain this answer?, a detailed solution for Two elements A and B form compounds AB2 and AB4 (both are non-volatile and non-electrolyte) when dissolved in 20.0 g benzene, 1 g of AB2 lowers the freezing point of benzene by 2.3 K, whereas 1.0 g of AB4 lowers it by 1.3 K [Kf (benzene) = 5.5 K mol-1 kg]. ; Thus, atomic masses of A and B respectively, ara)120,212b)96,28c)212,120d)28,46Correct answer is option 'D'. Can you explain this answer? has been provided alongside types of Two elements A and B form compounds AB2 and AB4 (both are non-volatile and non-electrolyte) when dissolved in 20.0 g benzene, 1 g of AB2 lowers the freezing point of benzene by 2.3 K, whereas 1.0 g of AB4 lowers it by 1.3 K [Kf (benzene) = 5.5 K mol-1 kg]. ; Thus, atomic masses of A and B respectively, ara)120,212b)96,28c)212,120d)28,46Correct answer is option 'D'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice Two elements A and B form compounds AB2 and AB4 (both are non-volatile and non-electrolyte) when dissolved in 20.0 g benzene, 1 g of AB2 lowers the freezing point of benzene by 2.3 K, whereas 1.0 g of AB4 lowers it by 1.3 K [Kf (benzene) = 5.5 K mol-1 kg]. ; Thus, atomic masses of A and B respectively, ara)120,212b)96,28c)212,120d)28,46Correct answer is option 'D'. Can you explain this answer? tests, examples and also practice JEE tests.
Explore Courses for JEE exam

Top Courses for JEE

Explore Courses
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev