Dobereiner arranged the element in increasing order of atomic masses. He found that the atomic mass of the middle element was approximately equal to the arithmetic mean (average) of the atomic masses of the other two elements of that triad when they are arranged in their increasing order of atomic mass.
1. Name the triad if the average of two atomic mass is 23.
a. Li, Na, K
b. Ca, Sr, Ba
c. Co, Fe, Ni
d. K, Ca, Li
2. How many triads did Dobereiner identify among the known elements?
a. 5
b. 6
c. 4
d. 3
3. Dobereiner's law of triad arranged the elements with similar properties in which section?
a. periods
b. groups
c. Both option 1 and 2
d. None
4. Which of the triads does not follow Dobereiner's law of triad ?
a. Be, Mg, Ca
b. Cu, Ag, Au
c. Ca, Sr, Ba
d. R, Bi, Be
5. E, F and G follows the Dobereiner's law of triad. Find the Atomic mass of F, if Atomic mass of E = 37 and and Atomic mass of G = 125
a. 46
b. 81
c. 75
d. 56
