Chemistry

Periodic Classification and Elements

1,176 Questions

Periodic classification organizes chemical elements based on atomic structure, periodic laws, and elemental properties. It covers historical classification systems, electron configurations, and periodic trends. Test takers preparing for chemistry sections will find these questions crucial for mastering fundamental element properties and atomic interactions.

Periodic table structureAtomic orbitalsElement identificationPeriodic laws

Periodic Classification and Elements Questions

Multiple choice evs look, learn and experience matter: states, classification and properties study of matter general introduction: importance and scope of chemistry

An atom of an element loses two electrons to form an ion. The quantum numbers of the electrons lost are $n = 4 :and :l = 0$. If another atom of the same element loses one more electron to form an ion, the quantum numbers (Principle and Azimuthal) of this electron lost are ________.

  1. 1,2

  2. 3,2

  3. 3,4

  4. 4,5
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Quantum number $n = 4,:l = 0$ corresponds to 4s electrons. When two 4s electrons are lost, a dipositive ion is formed. The configuration of the element could be $3s^23p^64s^2 :or :3s^23p^63d^{1-10} 4s^2$. Since the atom of the same element can lose one more electron, it should be the 'd' block element. 


Iron is the element showing +2 and +3 oxidation states, the configuration could be $3s^23p^63d^64s^2$. The $3^{rd}$ electron lost has quantum numbers $n = 3$, $ l=2$.$Fe^{+3}$  is smaller than $Fe^{+2}$ ion. This is because effective nuclear force of attraction in $Fe^{+3}$  is more than that in $Fe^{+2}$.

Multiple choice evs look, learn and experience matter: states, classification and properties study of matter general introduction: importance and scope of chemistry

Assuming that the number of maximum permissible shells is 5, elements would be there in the periodic table is:

  1. 52

  2. 54

  3. 55

  4. 51
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

According to Aufbau principle the order of filling of orbitals is:
$1s\ 2s\ 2p\ 3s\ 3p\ 4s\ 3d\ 4p\ 5s\ 4d\ 5p\ 6s\ 4f\ 5d\ 6p$
For maximum shell of 5, electrons will be filled upto 5p orbital as (each period)
$(1s^2)(2s^22p^6)(3s^23p^6)(4s^23d^{ 10 }4p^6)(5s^24d^{ 10 }5p^6)$
$2+8+8+18+18=54$
Therefore maximum number of atoms would be 54.
option B is correct.

Multiple choice chemistry 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

In Mendeleev's periodic table few elements that are chemically similar are placed in the same groups.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Mendeleev arranged the elements having similar configuration placed in the vertical columns as they will have the same unpaired electrons hence reflecting the similar properties. In Mendeleev's periodic table few elements that are chemically similar are placed in separate groups.

Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

Number of valence electrons present in atoms of $HClO _{4},HClO _{3},HClO _{2}$ respectively are :

  1. $32,26,20$
  2. $26,20,14$
  3. $36,30,24$
  4. $28,22,16$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Number of valence electrons present in atoms of $HClO _{4},HClO _{3},HClO _{2}$ are32,26,20 respectively.
Number of valence electrons present in atoms of  $HClO _{4}$ are $1+7+4(6)=32$
Number of valence electrons present in atoms of  $HClO _{3}$ are $1+7+3(6)=26$
Number of valence electrons present in atoms of  $HClO _{2}$ are $1+7+2(6)=20$

Multiple choice group 17 elements - trends in chemical properties group 17 elements - properties p- block elements-ii p-block elements chemistry

Elements in the halogen family belonging to 17th group in the periodic table show similarity in their properties .

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Similar properties:-

(i) Group 17 elements have high electronegativity than other groups.
(ii) They have high $e^-$ affinity than other groups.
(iii) Group 17 has high $e^-$ gain enthalpy.

Multiple choice group 17 elements - trends in chemical properties group 17 elements - properties p- block elements-ii p-block elements chemistry

Statement $1$: Element $Z$ with an electronic configuration of $1s^{2} 2s^{2} 2p^{5}$ can be expected to form the compound $MgZ _{2}$.
Statement $2$: Each atom of $Z$ needs two electrons to fill its valence shell.

  1. Both Statement $1$ and Statement $2$ are correct and Statement 2 is the correct explanation of Statement $1$
  2. Both Statement $1$ and Statement $2$ are correct, but Statement $2$ is NOT the correct explanation of Statement $1$
  3. Statement $1$ is correct, but Statement $2$ is not correct
  4. Statement $1$ is not correct, but Statement $2$ is correct
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Element Z has electronic configuration ${1s}^2 2s^2 2p^{5}$ , its belongs to 17th group so, it can form compound $MgZ _2$.

Its valency will be one.
It requires 9 elctron to fill its valence shell or it has already 9 electrons. So, statement 2 is wrong.
 

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

In Newland's classification, elements are arranged in an increasing order of their:

  1. mass number

  2. atomic number

  3. atomic weight

  4. all of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Newlands arranged elements in increasing order of their atomic weight and stated that every eighth element resembled properties of first element. This is Newland's law of Octaves. Hence correct answer for asked question is option C-atomic weight.

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

Which of the following is the correct set of elements to Dobereiner's triads ?

  1. Li - 7, Na - 23, K -39

  2. Br - 80, Cl - 35.5, I - 127

  3. Fe - 55.85, Ni - 58.71, Co - 58.93

  4. All of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Dobereiner's triads are a group of three elements in which the atomic mass of the middle element is equal to the average of atomic masses of the first and the third element.


For option A,
Average of atomic masses of first and last elements = $7+ \dfrac{39}{2} = 23$
This is the atomic mass of second element.

For option B.
Average of atomic masses of first and last elements = $80+ \dfrac{127}{2} = 103.5$
This is not the atomic mass of the second element.

For option C,
Average of atomic masses of first and last elements = $55.85+ \dfrac{58.93}{ 22} = 55.89$
This is not the atomic mass of the middle element.

Hence, the correct answer is option $A$.

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

Statement: In Dobernier classification of elements, the atomic weight of the middle element is equal to the average of the extreme elements of a triad.


State whether the given statement is true or false.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Dobereiner classified the elements into triads (group of three). He made the groups such that, the mass of middle element is the average of the mass of other $2$ elements. This is Dobernier's law of triads. 


Thus given statement is $\text{true}$.

Multiple choice physics rotational motion of a rigid body and moment of inertia angular momentum (l) and conservation of angular momentum angular momentum in case of rotation about a fixed axis law of conservation of angular momentum

$E _n$ and $J _n$ denote the total energy magnitude and the  angular momentum of an electron in the nth allowed orbit of the Both atom .Then:

  1. $E _n \pi J _n$
  2. $E _n \pi \frac {1} {J}$
  3. $E _n \pi { J } _{ n }^{ 2 }$
  4. $E _n \pi \frac {1} {J^2}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In the Bohr model, E is proportional to 1/n^2 and J (angular momentum) is proportional to n. Therefore, E is proportional to 1/J^2.

Multiple choice chemistry quantitative chemistry avogadro hypothesis avogadro's law avogadro law

If  $N _ { A }$ is Avogadro's number, then calculate the number of electrons in  $4.2\ g$  of  $N ^ { 3- }$.

  1. $2.1 N _ { A }$
  2. $3 N _ { A }$
  3. $6 N _ { A }$
  4. $ N _ { A }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
$N^{3-}$ contains 10 electrons.

Number of moles $= \dfrac {4.2}{14} $
                                     
                                       $=0.3\ moles$

No of electrons in $0.3\ moles = 0.3\times N _A\times 10$

                                        $=3\ N _A$

Hence, option B is correct.
Multiple choice imperfections in solids solid state the solid state chemistry

Metallic or non-stoichiometric (or interstitial) hydrides are formed by:

  1. Many d-block and f-block elements.

  2. Many s-block elements

  3. Many p-block elements

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Metallic or interstitial hydrides are typically formed by d-block and f-block transition metals where hydrogen occupies interstitial sites in the metal lattice.

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

The attempt for classifying elements by plotting the atomic masses of elements against the atomic volumes was made by:

  1. Dobereiner

  2. Newlands

  3. Lother Meyer

  4. Mendeleev
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

According to this if the atomic weights were plotted as ordinates and the atomic volumes as abscissae-the curve obtained a series of maxima and minima-the most electropositive elements appearing at the peaks of the curve in order of their atomic weights and electronegative element at the ascending positions.