Dobernier's Triads

Q.

In a Dobereiners triad, the atomic weights of first two elements are x and y. What should be the atomic weight of the $3$rd element?

1. $\text{x+y}$

2. $\text{x-y}$

3. $\text{x+2y}$

4. $\text{2y-x}$

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. 162.5
2. 91.5
3. 81.25
4. 45.625

Q.

A, B & C are the elements of the Dobereiner's triads. If the atomic mass of A is 7 and that of C is 23, then the atomic mass of B will be __.

Q. In a Dobereiner's triad, there are _______ elements.

1. three
2. four
3. two
4. five

Q. Identify the set of elements that will form Dobereiner triad.

1. Lithium, sodium, potassium
2. Nitrogen, phosphorus, arsenic
3. Helium, neon, argon
4. Helium, hydrogen, potassium

Q.

Which of the following can form Dobereiner’s triads with lithium (atomic mass = 6.9 u) and sodium (atomic mass = 23 u)?

1. Sulphur, atomic mass = 32 u

2. Calcium, atomic mass = 40 u

3. Chlorine, atomic mass = 35 u

4. Potassium, atomic mass = 39 u

Q.

Triads of elements arranged in increasing order of their atomic masses were proposed by-

1. Dobereiner

2. Dmitri Mendeleev

3. Ernest Rutherford

4. Lothar Meyer

Q.

Which of the following groups follows Dobereiner’s law of triads?

1. Sr, Ba, Ca

2. Br, Cl, I

3. Cl, Br, I

4. Li, K, Na

Q.

The elements in the Dobereiner’s triads follow:

1. The mass of middle element was roughly the average of atomic masses of other two elements.

2. Elements in the Triads show similar properties.

3. All the options are correct

4. The elements are written in increasing order of atomic mass.

Q.

Given below are the elements with their atomic masses. Identify a set of elements which is not a Dobereiner's triad.

1. N (14.0), P (31.0), As (74.9)
2. Li (6.9), Na (23.0), K (39.0)
3. Ca (40.1), Sr (87.6), Ba (137.3)
4. Cl (35.5), Br (79.9), I (126.9)

Q. Analyse the elements given below and identify ‘X’ if the given elements are forming Dobereiner's triad.

Li (6.9), Na (X), K (39.0)

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