Tag: mendeleev's periodic law and its limitations

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Multiple choice chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history
Which of the following is(are) the merit(s) of Mendeleev's periodic table?

  1. Could also predict the properties of these unknown elements

  2. Grouping of chemically dissimilar elements.

  3. Position given to isotopes.

  4. Presence of anomalous pairs.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
A)Mendeleev could also predict the properties of these unknown elements, on the basis of the properties of the elements lying adjacent to these vacant spaces.

He predicted the presence of three elements. They were named as Eka boron, Eka-aluminium and Eka-silicon. The properties of these three elements were similar to the actual elements discovered later.

Eka-boron was similar to Scandium, Eka-aluminium was similar to Gallium and Eka-silicon was similar to Germanium.

It is the merit of Mendeleev's periodic table and all other options are demerits of it.

B) Some elements placed in the same sub-group varies in the properties. 
     Ex. Manganese is placed with halogens which totally differ in properties.

C) Isotopes had to be given the same position though isotopes of the same elements have different atomic masses.

D) The element of higher atomic mass ex. Cobalt [58.93u] has been placed before an element of lower atomic mass ex. Nickel [58.71u]. 
     These are anomalous pairs.

Hence, the correct option is $\text{A}$
Multiple choice chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

Which among the following is not an anomalous pair in Mendeleev's periodic table?

  1. Co, Ni

  2. Te, I

  3. Ar, K

  4. Sc, Ga
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In certain pair of elements, the increasing order of atomic masses was not obeyed. 


In these, Mendeleev placed elements according to similarities in their properties and not in increasing order of their atomic masses.

 The last pair is not anomalous pair.

Option D is correct.

Multiple choice chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

The chemical formula of the oxide of $Eka\ -$ aluminium is:

  1. $GaO$
  2. $GaO _2$
  3. $Ga _2O _2$
  4. $Ge _2O _3$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$Eka$-aluminium is known as $Gallium$.


Gallium forms only two oxides as ${Ga} _{2}O$ or ${Ga} _{2}{O} _{3}$.

It's is in $+1$ and $+3$ oxidation state$.$.

Therefore, the correct option is $D$.

Multiple choice chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

Cycloalkanes are isomeric with

  1. Alkenes

  2. Alkanes

  3. Alkynes

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

Cycloalkanes are isomeric with alkenes because they have the same general formula CnH2n but possessing different structures, shows ring chain isomerism. Example- cyclohexane $(C _6H _12)$ and hexene $(C _6H _12)$ are ring chain isomers.

Multiple choice chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

The first element of a group in many ways differs from the other heavier members of the group. This is due to:

  1. the small size

  2. the high electronegativity and high ionisation potential

  3. the unavailability of d-orbitals

  4. all of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

1st element of a group, have smaller size and high IP, also they dont have d-orbitals so they show different properties like valency, ionic character, maximum valency solubility.

Multiple choice chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

Write the correct alternatives :
According to Mendeleev's periodic law, properties of elements are periodic function of their...............

  1. Atomic number

  2. Atomic masses

  3. Densities

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

According to Mendeleev's law, the physical and chemical properties of element are the periodic function of their atomic weights . (atomic masses)


$\therefore$ option "B" is correct.

Multiple choice chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

Which of the following is incorrect statement about Mendeleev's classification of elements?

  1. He could classify all the elements including noble gases.

  2. He left gaps for some yet to be discovered elements.

  3. He predicted the properties of some undiscovered elements.

  4. There was no place for isotopes in his table.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Mendeleev periodic table is based on atomic weights of elements,

$\left( \ast  \right) $ He left no place for isotopes in his table.
$\left( \ast  \right) $ Predicted the properties and left gaps for discovered elements.
$\left( \ast  \right) $ He could not classify all elements including noble gases.
Ans :- A.

Multiple choice chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

Consider the following statements:
(a) The discovery of inert gases later on did not disturb Mendeleev's arrangement.
(b) In his classification of element, Mendeleev was guided proportional to two factors.
(c) In the present periodic table, periodicity in the properties of elements is related to the periodicity in their electronic configurations. 


Which of the above statement(s) is/are correct?

  1. Only (a)

  2. Only (c)

  3. (a) and (b)

  4. (a), (b) and (c)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

a.)The discovery of inert gases, later on, did not disturb Mendeleev's arrangement as he made quite clear that the noble gas must reside in the periods of inert gases having their octet i.e.completely filled electrons in their valence shell.


b.)In the classification of elements, Mendeleev was guided proportional to by two factors which were their atomic voice and their chemical properties.

c.)In the present periodic table, periodicity in the properties of elements is related to the periodicity in their electronic configurations. 

Hence it is (a), (b) and (c)

Multiple choice chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

Which of the following is the correct match?
(a) Eka silicon - $\text{Ge}$
(b) Eka aluminum - $\text{Ga}$
(c) Eka manganese - $\text{Tc}$
(d) Eka boron - $\text{Sc}$

  1. b, c

  2. a, b, d

  3. a, d

  4. All of above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Eka is a-prefix used to designate the first element of the same family in the periodic table beyond the one to whose name it is prefixed, as Eka manganese

(a) Eka silicon - Ge (germanium)

(b) Eka aluminium - Ga (gallium )

(c) Eka manganese - Tc (technetium) 

(d) Eka boron – Sc (scandium)

Hence, the correct option is $\text{D}$
Multiple choice chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

Mendeleev's classified elements in:

  1. Increasing order of atomic number

  2. Increasing order of atomic masses

  3. Decreasing order of atomic masses

  4. Decreasing order of atomic number
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Mendeleev's law
"the statement that the chemical and physical properties of the elements recur periodically when the elements are arranged in the order of their atomic weights."