Dobereiner's Triads

Q.

Did Dobereiners triads also exist in the columns of Newland's Octaves ? Compare and find out.

Q.

If the empirical formula of an organic compound is $C{H}_{2}O$, then its molecular formula can be

1. C₂H₂O

2. C₂H₄O

3. C₃H₆O

4. C₆H₁₂O₆

Q.

(a) A, B and C are the elements of a Dobereiner's triad.If the atomic mass of A is 7 and that of C is 39, what should be the atomic mass of B?

(b) Why was Dobereiner's triad discarded ?

Q. Identify a Dobereiner triad from the following.

1. Li, Na, K
2. N, P, As
3. He. Ne, Ar
4. Li, Ca, K

Q.

The Dobereiner's Triad given to you is Li, Na and K. If the atomic masses of Na and K in the Dobereiner's Triad is 23 and 39 respectively. Find the atomic mass of Lithium.

1. 7

2. 7.5

3. 6.5

4. 6

Q. If Dobereiner is related with ‘law of triads’, then Newlands is related with​

1. Pauli exclusion principle
2. Hunds Rule
3. Law of octaves
4. Modern periodic law

Q.

Combine $0.2g$ atoms of silicon with $21.3g$ of chlorine. Find the empirical formula of the compound formed.

Q.

The number of moles of C₂H₅OH which will weigh 138g is ______

Q.

What are known as triads?

Q. Identify the option that is not one of the Dobereiner's triad?

1. Chlorine-35, Bromine-80, Iodine-127
2. Potassium-39, Chlorine-35.5, Bromine-80
3. Calcium-40, Strontium-88, Barium-137
4. Lithium-6, Sodium-22, Potassium-39

Q. If Cl, Br, I, is a Dobereiner's triad and the atomic masses of Cl and I are 35.5u and 127u respectively, then the atomic mass of Br is

1. 91.5
2. 45.625
3. 81.25
4. 162.5

Q.

In the given periodic table the coloured boxes represents elements and are grouped as _______________

1. Alkalies

2. Halogens

3. Dobereiner triads

4. Noble gases

Q. What were the limitations of Dobereiner’s classification ?

Q. In Dobereiner's triads, when three elements in a triad are written in the increasing order of atomic masses; the atomic mass of the middle element is roughly the average of the atomic masses of the other two elements. Identify ‘X’ from the given triad.
Li (6.9), Na (X), K (39.0).

1. 23.0
2. 19.0
3. 15.3
4. 45.9

Q.

If the atomic weight of chlorine is 35.5 and the atomic weight of iodine is 126.5, what is the expected atomic weight of bromine? Explain logically.

Q. Dobereiner grouped the elements into triads and Newland gave the:

1. Law of constant proportion
2. Law of Octaves
3. Law of multiple proportion
4. None of these

Q. Which of the following are chemical symbols of a noble gases?

1. He
2. Xe
3. Ne
4. N
5. Ar
6. Kr
7. Cl
8. F

Q.

Which of the following can form Dobereiner's Triads with Li(A = 6.9) and sodium (A = 23)?

1. K (A = 32)

2. K (A = 37)

3. K (A = 45)

4. K (A = 39)

Q. Lithium, sodium and potassium form a Dobereiner’s triad. The atomic masses of lithium and potassium are 7 and 39 respectively. Predict the atomic mass of sodium.

Q. Lithium, sodium and potassium form a Dobereiner’s triad. The atomic masses of lithium and potassium are 7 and 39 respectively. Predict the atomic mass of sodium.

Q.

it is said that as per dobereiner`s classification, most elements were in groups of three , that means not all elements classified by him were in groups of three . Give an example in which the group classified by him were not in groups of three.

Q. Did Dobereiners traids also exist in the columns of Newland's Octaves? Compare and find out.

Q.

The ratio of a gram atomic weight of nitrogen and oxygen is___.

Q.

X (atomic mass = 37), Y (atomic mass = 81), and Z are three members of Dobereiner's triads. Atomic mass of Z=?

1. None of the above

2. 59

3. 125

4. 130

Q.

If chlorine, bromine and iodine form a Dobereiner's triad and the atomic masses of chlorine and iodine are 35.5 u and 127.0 u respectively, then the atomic mass of bromine is _____.

1. 81 u

2. 45 u

3. 162 u

4. 91 u

Q.

Three elements X, Y and Z formed a dobereiners triad. The ratio of the atomic weight of X to that of Z is 7:25, if the sum of atomic weight of X and Z is 160, find the atomic weight of X, Y and Z.

Q. Three elements X, Y and Z form a Dobereiner triad. The ratio of the atomic weight of X to that of Z is 7: 25.

1. X $\to$ 125, Y $\to$ 80, Z $\to$ 35
2. X $\to$ 35, Y $\to$ 80, Z $\to$ 125
3. X $\to$ 80, Y $\to$ 35, Z $\to$ 125
4. X $\to$ 80, Y $\to$ 125, Z $\to$ 35