Tag: the periodic table

Quizzes (8) Questions (146)

Questions Related to the periodic table

Multiple choice chemistry the periodic table dobereiner's triads development of the modern periodic table into the history

Atomic wt. of P is 31 and Sb is 120. What will be the atomic wt. of As, as per Dobernier triad rule?

  1. $151$
  2. $75.5$
  3. $89.5$

  4. Unpredictable
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Atomic wt. of P is 31 and Sb is 120. The atomic wt. of As, as per Dobernier triad rule will be average of two. It will be $\displaystyle \frac {31+120}{2} = \frac {151}{2} =75.5 $

Multiple choice chemistry the periodic table dobereiner's triads development of the modern periodic table into the history

If three elements X, Y, and Z form a Dobereiner's triad and atomic weights of X and Z are 9 and 40 respectively, then the atomic weight of the element Y is approximately:

  1. 24.5

  2. 49

  3. 34.5

  4. 29
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

According to Dobereiner, the atomic weight of the central element of the triad is the arithmetic mean of the atomic weights of the other two members. 


Therefore, atomic weight of Y = $\cfrac{9 + 40}{2} = 24.5\ g$


Hence, option A is correct.

Multiple choice chemistry the periodic table dobereiner's triads development of the modern periodic table into the history

Law of Triad was proposed by:

  1. Newland

  2. Gay Lussac

  3. Mendeleev

  4. Dobereiner
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Dobereiner, in 1817 suggested a relationship between the properties of elements and their atomic weights. According to Dobereiner, the atomic weight of the middle element is nearly the same as average of the atomic weights of other two elements.

Multiple choice chemistry the periodic table dobereiner's triads development of the modern periodic table into the history

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.


 If the sum of the atomic weights of X and Z is 160, find the atomic weights of X, Y and Z.

  1. X $\rightarrow$ 35, Y $\rightarrow$ 80, Z $\rightarrow$ 125
  2. X $\rightarrow$ 125, Y $\rightarrow$ 80, Z $\rightarrow$ 35
  3. X $\rightarrow$ 80, Y $\rightarrow$ 35, Z $\rightarrow$ 125
  4. X $\rightarrow$ 80, Y $\rightarrow$ 125, Z $\rightarrow$ 35
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Let weight of X be $7a$  $\therefore$ Atomic weight of $Z=25a$

$\therefore7a+25a=160$

$\Rightarrow a=5$

Weight of X$=35$ and of Z is $125$

Atomic weight of Y is arranged of X and $2=\cfrac { 35+125 }{ 2 } =80$

Hence, the correct option is $\text{A}$
Multiple choice chemistry the periodic table dobereiner's triads development of the modern periodic table into the history

When a Dobereiner triad is considered, the sum of atomic weights of extreme elements X and Z is 177.6 and difference of Z and Y is five times the number of protons present in a neon atom. Identify X, Y and Z.

  1. $X \rightarrow Ca, Y \rightarrow Sr, Z \rightarrow Ba$
  2. $X \rightarrow Li, Y \rightarrow Na, Z \rightarrow K$
  3. $X \rightarrow K, Y \rightarrow Rb, Z \rightarrow Cs$
  4. $X \rightarrow Sr, Y \rightarrow Ba, Z \rightarrow Ra$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The atomic weight of Y is avergae of X and Z
$\therefore { M } _{ Y }=\cfrac { 177.6 }{ 2 } =88.8$
$88.8$ is weight of Sr. So Y is Sr. According to this only option A is correct.
Multiple choice chemistry the periodic table dobereiner's triads development of the modern periodic table into the history

Which of the following sets of atomic masses do not correspond to Dobernier traid?

  1. $7, 23, 39$
  2. $20, 38, 56$
  3. $47, 91, 178$
  4. $54, 95, 183$
Reveal answer Fill a bubble to check yourself
C,D Correct answer
Explanation

The following sets of atomic masses do not correspond to Dobernier traid.
(C) $\displaystyle 47, 91, 178$
(D) $\displaystyle 54, 95, 183$
In these sets, the atomic mass of middle element is not equal to the mean of atomic masses of first and last element.
$\displaystyle 91 \neq \dfrac {47+178}{2}$
$\displaystyle 95 \neq \dfrac {54+183}{2} $

Multiple choice chemistry the periodic table dobereiner's triads development of the modern periodic table into the history

Dobereiner was the first person to illustrate the relationship between the ____________ of elements and their properties.

  1. atomic masses

  2. electron negativity

  3. molecular masses

  4. number of protons
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Dobereiner grouped elements in set of triads. Thus each group had 3 elements. Dobereiner classified elements into groups based on their properties. He illustrate the relationship between the atomic masses of elements and their properties with his law of triads.