Question

Two elements A and B form compounds having molecular formula AB2 and AB4. When dissolved in 20g of benzene, 1g of AB2 lowers the freezing point by 2.3k, whereas 1.0g of AB4 lowers it by 1.3k. The molar depression constant for benzene is 5.1k kg/mol.
Calculate the atomic mass of A and B.
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Answer 1

Answer:

As we know that,

MB=(kf×WB×1000)/(WA×deltaTf)

Now deltaTf =2.3, WB=1.0, WA=20,KF=5.1( given)

putting tye values in the equation.

MB=(5.1×1×1000)/(20×2.3)

=110.87 g/mol

Therefore Mab2=110.9

for AB4 compound

delta Tf=1.3,WB=1,Wa=20

MB=(5.1×1×1000)/(20×1.3)

=196g/mol

therefore MAB=196

Let x be the atomic masw of Aand y be the atomic mass of B

Then MAB2=x+2y=110.9______(1)

&MAB=x+4y=196________(2)

subtracting (2)from(1)

we get,

2y=196-110.9

y=85.1/2

y= 42.6

putting tye value of y in (1)

we get,

x=110.9 -2×42.6

x=25.59

Therefore, Atomic mass of A=25.59U and Atomic mass of B =42.6U.

Hope it helps you❤

Answer 2

$\huge\mathfrak{Answer}$

⭐Resistivity is a measure of the resistance of a given size of a specific material to electrical conduction .

⭐Materials that conduct electrical current easily are called conductors and have a low resistivity. Those that do not conduct electricity easily are called insulators and these materials have a high resistivity.