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प्रश्न
The three imaginary elements X, Y and Z represent a Dobernener's triad. If the atomic mass of element X is 14 and that of element Y is 46, then the atomic mass of element Z will be:
(a) 28
(b) 60
(c) 78
(d) 72
उत्तर
(c) 78
The atomic mass of the element Z is 78.
According to Dobereiner's law of triads, atomic mass of `Y=(X+Z)/2`
Substituting the atomic masses we get:
`46=(14+Z)/2`
92 = 14+Z
Therefore, Z = 78
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संबंधित प्रश्न
Name the scientist who gave Law of triads in the early classification of elements.
What is Debereiner's law of triads? Explain with the help of one example of a Dobereiner's triad.
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.
Can the following groups of elements be classified as Dobereiner's triads?
(a) Na, Si, Cl
(b) Be, Mg, Ca
Give reason for your answer.
(Atomic masses : Be 9 ; Na 23 ; Mg 24 ; Si 28 ; Cl 35.5 ; Ca 40)
Why was Dobereiner's triad discarded?
Can the following groups of elements be classified as Dobereiner's triad:
Na, Si, Cl
Atomic mass of Na - 23, Si - 28, Cl - 35.
Justify your answer.
Write the characteristic of Dobereiner’s triads?
Write the name.
The atom having the biggest atomic size from period 2.
State Dobereiner’s Law of Triads.
Match the following.
| 1. | Triads | Newlands |
| 2. | Alkali metal | Calcium |
| 3. | Law of octaves | Henry Moseley |
| 4. | Alkaline earth metal | Sodium |
| 5. | Modern Periodic Law | Dobereiner |
