Question

The atomic masses of three elements X, Y and Z having similar chemical properties are 7, 23 and 39 respectively.
(a) Calculate the average atomic mass of elements X and Z.
(b) How does the average atomic mass of elements X and Z compare with the atomic mass of element Y?
(c) Which law of classification of elements is illustrated by this example?
(d) What could the elements X, Y and Z be?
(e) Give another example of a set of elements which can be classified according to this law.

Answer 1

Answer:

average is 23=x+z/2

because these are called dobereiner triads .once read law what dobereiner says

x is lithium

y sodium

z potassium

other example is

(oxygen, sulphur, selenium)

chlorine, bromine, iodine

Answer 2

Explanation:

(a) Average atomic mass =2Mass of X + Mass of Z

                                          =27+39=23

(b) The average atomic mass of elements X and Z is equal to the atomic mass of element Y.

(c) Dobereiner's law of triads is illustrated by this example.

(d) X is lithium, Y is sodium and Z is potassium.

(e) Chlorine, Bromine and Iodine is another such set..

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