Two elements A and B form compounds of formula A B₂ and A B₄ . When dissolved in 20.0 ~g of benzene 1.0 ~g of A B₂ lowers f. pt. by 2.3^ C whereas 1.0 ~g of A B₄ lowers f . pt. by 1.3^ C . The K_f for benzene is 5.1. The atomic masses of A

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Two elements A and B form compounds of formula A B₂ and A B₄ . When dissolved in 20.0 ~g of benzene 1.0 ~g of A B₂ lowers f. pt. by 2.3^ C whereas 1.0 ~g of A B₄ lowers f . pt. by 1.3^ C . The K_f for benzene is 5.1. The atomic masses of A and B are

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Correct answer: A. 25,42

Let the masses of A and B be a and b . The mass of A B₂ will be (a+2 b) g mol ⁻¹ and A B₄ will be (a+4 b) g mol ⁻¹ . T_f= K_f W_B 1000 M_B W_A On solving (i) and (ii), we get a=25.59 and b=42.64

Two elements A and B form compounds of formula A B₂ and A B₄ . When dissolved in 20.0 ~g of benzene 1.0 ~g of A B₂ lowers f. pt. by 2.3^ C whereas 1.0 ~g of A B₄ lowers f . pt. by 1.3^ C . The K_f for benzene is 5.1. The atomic masses of A and B are

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