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The valence of sodium with atomic number 11 is:
  • a)
    4
  • b)
    1
  • c)
    3
  • d)
    2
Correct answer is option 'B'. Can you explain this answer?

Rohan Singh answered
For Sodium Na - 2,8,1 and chlorine Cl-2,8,7. Both Na and Cl require 1 electron either to loose or to gain ,so they can attain stable configuration. Therefore Na has +1 and Cl -1 valency. Valence electrons are the outermost electrons, and are the ones involved in bonding.

In Na2O oxidation state of oxygen is:​
  • a)
    +2
  • b)
    -1
  • c)
    0
  • d)
    +1
Correct answer is option 'D'. Can you explain this answer?

Geetika Shah answered
In Na2O oxidation state of Na is +1.
It gains 2 electrons so, the oxidation state is +1 which is equal to one oxygen atom (2 electrons)

Lothar Meyer proposed that on arranging the elements in order of increasing atomic weights; similarities appear in which type of properties?
  • a)
    Only physical properties
  • b)
    Only chemical properties
  • c)
    In both physical and chemical properties
  • d)
    thermodynamic properties
Correct answer is option 'C'. Can you explain this answer?

Anoushka Yadav answered
Lothar Meyer proposed the periodic table in 1864. He arranged the elements in order of increasing atomic weights. He noticed that similarities appeared in both physical and chemical properties of the elements. The correct answer is option 'C' which means similarities appear in both physical and chemical properties.

Explanation:
The periodic table arranges the elements in a way that helps in understanding their properties. The modern periodic table is based on the electronic configuration of the elements. But the original periodic table was based on the atomic weight of the elements. Lothar Meyer was the first to realize that there is a periodicity in the properties of the elements when they are arranged in order of increasing atomic weights.

Physical properties are those that can be observed or measured without changing the chemical composition of the substance. Some examples of physical properties are:

- Melting point
- Boiling point
- Density
- Electrical conductivity
- Thermal conductivity
- Atomic radius
- Ionic radius
- Electronegativity

Chemical properties are those that can be observed during a chemical reaction. Some examples of chemical properties are:

- Reactivity with acids
- Reactivity with oxygen
- Reactivity with water
- Reduction potential
- Oxidation potential

Meyer observed that when the elements are arranged in order of increasing atomic weights, there is a periodicity in their physical and chemical properties. This means that elements with similar atomic weights have similar physical and chemical properties. For example, lithium, sodium, and potassium have similar physical and chemical properties because they all belong to the same group and have similar atomic weights.

Conclusion:
Lothar Meyer proposed the periodic table in 1864. He arranged the elements in order of increasing atomic weights. He noticed that similarities appeared in both physical and chemical properties of the elements. When the elements are arranged in order of increasing atomic weights, there is a periodicity in their physical and chemical properties.

Sodium forms which types of oxides?
  • a)
    Acidic
  • b)
    Basic
  • c)
    Neutral
  • d)
    Amphoteric
Correct answer is option 'B'. Can you explain this answer?

Pooja Mehta answered
Basic oxides are always oxides of metals. They combine with water to form bases which are usually called metal hydroxides. Na2O, MgO, CaO, FeO and CuO are examples of basic oxides. Acidic oxides are mostly oxides of non-metals, and they dissolve in water to form acids.

Horizontal rows in the periodic table are called:
  • a)
    Cell
  • b)
    Table
  • c)
    Groups
  • d)
    Periods
Correct answer is option 'D'. Can you explain this answer?

Rohan Singh answered
The Periodic Table: Families and Periods. In the periodic table of elements, there are seven horizontal rows of elements called periods. The vertical columns of elements are called groups, or families.

Can you explain the answer of this question below:

In the modern periodic table, which period contains 32 elements?

  • A:

    Sixth

  • B:

    First

  • C:

    Seventh

  • D:

    Second

The answer is a.

Preeti Iyer answered
The answer is c.
The total number of electrons that can be accommodated in seventh period are 2 ( in 7s) + 14(in 5f) + 10(in 6d )+ 6(in 7p) = 32. The maximum number of elements present in it is 32.

An element with atomic number will form a basic oxide________        
  • a)
    7        
  • b)
    17        
  • c)
    14        
  • d)
    11
Correct answer is option 'D'. Can you explain this answer?

EduRev NEET answered
Sodium forms a basic oxide because it is a metal. Metals generally form basic oxides because they tend to donate electrons to oxygen atoms. In the case of sodium, when it reacts with oxygen, it forms sodium oxide, in which each sodium atom donates one electron to oxygen. This results in the formation of sodium ions (Na+) and oxide ions (O2-), which can combine to form the ionic compound sodium oxide. Sodium oxide is basic because it can react with water to form a solution of sodium hydroxide, a strong base.
 

Which electronic configuration of an element has abnormally high difference between second and third ionization energy ? [1993]
  • a)
    1s2, 2s2, 2p6, 3s1
  • b)
    1s2, 2s2, 2p6, 3s1 3p1
  • c)
    1s2, 2s2, 2p6, 3s2 3p2
  • d)
    1s2, 2s2, 2p6, 3s2
Correct answer is option 'D'. Can you explain this answer?

Shivani Tiwari answered
In option D, after removal of second valence electron from 3s orbital, the ion formed achieves noble gas configuration. Therefore, to remove the third electron from 2p orbital, a lot of energy is required. Thus, there is an abnormally high difference between second and third ionization enthalpies.

Which block of the periodic table contains the man made elements?
  • a)
    p block
  • b)
    s block
  • c)
    f block
  • d)
    d block
Correct answer is option 'C'. Can you explain this answer?

Raghav Bansal answered
Most of the f block elements, lanthanoids and actinoids are man made/synthetic/prepared in the lab. Especially actinoids.

Where would you find the smallest atoms of elements in the periodic table?
  • a)
    top and right hand side
  • b)
    top and left hand side 
  • c)
    bottom and left hand side
  • d)
    bottom and right hand side
Correct answer is option 'A'. Can you explain this answer?

The smallest atom is the one with the smallest number of protons. This is hydrogen, located in the top left side of the periodic table. Hydrogen is particularly small because the most common isotope doesn't have a neutron, plus it readily loses its electron.

Eka silicon predicted by Mendeleev is which element:
  • a)
    Germanium
  • b)
    Aluminium
  • c)
    Gallium
  • d)
    Sodium
Correct answer is option 'A'. Can you explain this answer?

Suresh Iyer answered
Mendeleev predicted the existence of 'eka-silicon', which would fit into a gap next to silicon. The element germanium was discovered later. Its properties were found to be similar to the predicted ones and confirmed Mendeleev's periodic table.

Which of the following pairs have both the members from the same group of periodic table?
  • a)
    Mg, Cl
  • b)
    Mg, Cu
  • c)
    Mg, Be
  • d)
    Mg, Na
Correct answer is option 'C'. Can you explain this answer?

Neha Joshi answered
The elements in the group include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).

Which of the following is the most non-metallic element?
  • a)
    F
  • b)
    Si
  • c)
    N
  • d)
    B
Correct answer is option 'A'. Can you explain this answer?

Nandini Patel answered
The non-metallic character increases as we go from left to right across the periodic table. Hence, fluorine (F) is most non-metallic. Further F has maximum tendency to accept an electron characteristic of non-metal.

Na+ is smaller than Na atom because:
  • a)
    The effective nuclear charge is greater in case of sodium ion.
  • b)
    Nucleus in each case contains different nucleons.
  • c)
    Na+ is more stable than in Na atom.
  • d)
    Sodium atom has one electron lesser than sodium ion.
Correct answer is option 'A'. Can you explain this answer?

Geetika Shah answered
According to the electronic configuration of sodium(Na),it has 1 valence electron(2,8,1).So it loses one electron to form a cation and becomes sodium cation (Na+).As it loses one electron ,the outermost shell has 0 electrons (i.e it gets eliminated ) and Na+ has only 2 shells. Hence, it lost one of its shell, the sodium ion is smaller than the sodium atom.

What is the relationship between the number of elements in each period and the number of atomic orbitals available in the energy level that is being filled?
  • a)
    Number of elements is twice the number of atomic orbitals.
  • b)
    Number of elements is three times the number of atomic orbitals.
  • c)
    Number of elements is half the number of atomic orbitals.
  • d)
    Number of elements is same as the number of atomic orbitals.
Correct answer is 'A'. Can you explain this answer?

Krishna Iyer answered
The number of elements in each period is twice the number of atomic orbitals available in the energy level that is being filled.
Let's understand it by taking the elements of the 4th period.
In the fourth period, there are 18 elements. The types of subshells used in the 4th period are s, p, and d.
Number of orbitals of s subshell = 1
Number of orbitals of p subshell = 3
Number of orbitals of d subshell = 5
Total number of orbitals = 9
The total number of elements is 18 i.e. twice the total number of orbitals.

Which of the following is an ionic hydride?
  • a)
    PH3
  • b)
    H2S
  • c)
    HI
  • d)
    KH
Correct answer is option 'D'. Can you explain this answer?

Mohit Rajpoot answered
Ionic hydrides are commonly known as saline hydrides or pseudohalides. These compounds form between hydrogen and the most active metals, especially with the alkali and alkaline-earth metals of group one and two elements.
 
In this group, the hydrogen acts as the hydride ion (H−). They bond with more electropositive metal atoms. Ionic hydrides are usually binary compounds (i.e., only two elements in the compound) and are also insoluble in solutions. Now I hope you can form your own examples, but common examples are Sodium Hydride (NaH), Lithium hydride (LiH), Potassium hydride (KH) etc.

Elements in the same group have same:
  • a)
    Number of valence electrons
  • b)
    Density
  • c)
    Atomic radius
  • d)
    Nuclear charge
Correct answer is option 'A'. Can you explain this answer?

Lavanya Menon answered
  • Elements in the same group have the same number of valence electrons in their outermost shell, hence, have similar properties.
  • Elements in the same period don't have same number of valence electrons, hence, have different properties. But, elements in the same period have same number of shells. 

If the atomic number of an element is 33, it will be placed in the periodic table in the
  • a)
    First group
  • b)
    Third group
  • c)
    Fifteenth group
  • d)
    Seventh group.
Correct answer is option 'C'. Can you explain this answer?

Preeti Iyer answered
The electronic configuration of element with atomic number 33 is 1s22s22p63s23p63d104s24p3
As, its last shell have five electrons
and hence, its group is 10 + 5 = 15th or V A.
Hence,it lies in the 15th group.
 

The symbol for element with atomic number 111 and name Unununnium is
  • a)
    Uun
  • b)
    Uuu
  • c)
    UUU
  • d)
    None of the above
Correct answer is option 'B'. Can you explain this answer?

Gaurav Kumar answered
  • The element was to be called unununium (with the corresponding symbol of Uuu),a systematic element name as a placeholder, until the element was discovered (and the discovery then confirmed) and a permanent name was decided on.
  • Although widely used in the chemical community on all levels, from chemistry classrooms to advanced textbooks, the recommendations were mostly ignored among scientists in the field, who called it element 111, with the symbol of E111, (111) or even simply 111.

Among the elements with atomic numbers 9, 12, 16 and 36 which is highly electropositive?
  • a)
    Element with atomic number 9
  • b)
    Element \vith atomic number 12
  • c)
    Element with atomic number 16
  • d)
    Element with atomic number 36
Correct answer is option 'B'. Can you explain this answer?

Introduction:
In order to determine which element is highly electropositive among the elements with atomic numbers 9, 12, 16, and 36, we need to understand the concept of electronegativity and how it relates to electropositivity. Electronegativity is a measure of an atom's ability to attract electrons towards itself in a chemical bond. Electropositivity, on the other hand, is the tendency of an atom to lose electrons and form positive ions. Therefore, an element with low electronegativity and high electropositivity will readily lose electrons and form positive ions.

Explanation:
Let's analyze each element and its electropositivity based on their atomic numbers:

Element with atomic number 9 (Fluorine):
Fluorine is a halogen and has a high electronegativity. It readily gains an electron to achieve a stable electron configuration. Therefore, it is not highly electropositive.

Element with atomic number 12 (Magnesium):
Magnesium is an alkaline earth metal and has a low electronegativity. It readily loses its two valence electrons to achieve a stable electron configuration. Therefore, it is highly electropositive.

Element with atomic number 16 (Sulfur):
Sulfur is a nonmetal and has a moderate electronegativity. It can gain or lose electrons depending on the reaction conditions. However, it is not highly electropositive as it tends to gain electrons to achieve a stable electron configuration.

Element with atomic number 36 (Krypton):
Krypton is a noble gas and has a very high electronegativity. It has a stable electron configuration and tends not to lose or gain electrons. Therefore, it is not highly electropositive.

Conclusion:
Based on the analysis, the element with atomic number 12 (Magnesium) is highly electropositive among the elements with atomic numbers 9, 12, 16, and 36. It has a low electronegativity and readily loses its two valence electrons to form a stable 2+ ion.

Eka aluminium predicted by Mendeleev is which element?
  • a)
    Germanium
  • b)
    Magnesium
  • c)
    Gallium
  • d)
    Sodium
Correct answer is option 'C'. Can you explain this answer?

Gaurav Kumar answered
Eka aluminium predicted by Mendeleev is Gallium. Eka-aluminium and gallium are the two names of the same element as Eka -Aluminum has almost exactly the same properties as the actual properties of the gallium element. 

According to Dobereiner’s law of triads the number of elements present in each group is:
  • a)
    2
  • b)
    4
  • c)
    5
  • d)
    3
Correct answer is option 'D'. Can you explain this answer?

Geetika Shah answered
  • According to Dobereiner's law of triads each triad contains three elements.
  • He also noticed that the middle element of each of the triads had an atomic weight about halfway between the atomic weights of the other two.

The oxygen family is also known as:
  • a)
    halogen family
  • b)
    oxo family
  • c)
    chalcogen family
  • d)
    peroxo family
Correct answer is option 'C'. Can you explain this answer?

Rajat Kapoor answered
The Oxygen family, sometimes also known as chalcogens, is group 16 on the periodic table and consisted of oxygen, sulfur, selenium, tellurium, polonium and ununhexium.

The electronegativity of following elements increases in the order of?
  • a)
    Si, P, C, N
  • b)
    P, Si, N, C
  • c)
    C, N, Si, P
  • d)
    N, Si, C, P
Correct answer is option 'A'. Can you explain this answer?

Pooja Shah answered
Si,P,C,N
Electronegativity increases along a period and decreases down the group.Nitrogen is expected to have maximum electronegativity.

The first period has how many orbitals?
  • a)
    1
  • b)
    3
  • c)
    2
  • d)
    4
Correct answer is option 'A'. Can you explain this answer?

Raghav Bansal answered
1st period contains only 2 elements hydrogen and helium having atomic no. 1 and 2 respectively.
The electronic configuration of hydrogen is 1s1 while that of helium is 1s2. Both contain only s subshell. S subshell that only contains 1 orbital i.e. z.
Thus, 1st period has 1 orbital.

Johann Dobereiner classified elements in group of three elements called as
  • a)
    Trinity
  • b)
    Trials
  • c)
    Triads
  • d)
    Diads
Correct answer is option 'C'. Can you explain this answer?

Om Desai answered
In 1829, Johann Dobereiner, a German scientist made some groups of three elements each and called them triads.
He observed that the atomic mass of the middle element of a triad was nearly equal to the arithmetic mean of the atomic masses of the other two elements. All three elements of a triad were similar in their properties.

Which of the following elements will have the largest atomic radii?
  • a)
    Sr
  • b)
    Al
  • c)
    Li
  • d)
    Ca
Correct answer is option 'A'. Can you explain this answer?

Pooja Shah answered
Strontium has the highest atomic radii because it on the group atomic radius increases also it belongs to 4D so if there is doubt of Lanthanide contraction then the size of 4D is largest followed by 3D and 5D has the smallest size.

Among the following oxides, neutral oxide is:​
  • a)
    ZnO2
  • b)
    SiO2
  • c)
    CO
  • d)
    SnO2
Correct answer is option 'C'. Can you explain this answer?

Shreya Gupta answered
Neutral oxide. Neutral oxides are oxides which are neither acidic nor basic. In other words, oxides which neither react with acids or with bases are called neutral oxides. Some examples of neutral oxides are nitrous oxide (N2O), and carbon monoxide (CO).

Which of the following elements has the largest ionisation enthalpy?
  • a)
    O
  • b)
    F
  • c)
    C
  • d)
    N
Correct answer is option 'B'. Can you explain this answer?

Gaurav Kumar answered
Ionisation energy increases along a period. The very next elements C,N,O,F results F with higher ionisation energy.

Mendeleev predicted the existence of which element/elements in the periodic table?
  • a)
    Gallium
  • b)
    Sodium and germanium
  • c)
    Gallium and germanium
  • d)
    Germanium and Gold
Correct answer is option 'C'. Can you explain this answer?

Neha Joshi answered
Gallium and Germanium were the elements not discovered at that time and Mendeleev put gaps in the periodic table.
Gallium was called as Eka aluminium
Germanium was called as Eka silicon

Which one of the following oxides is expected to exhibit paramagn etic beh aviour? [2 00 5]
  • a)
    CO2
  • b)
    SiO2
  • c)
    SO2
  • d)
    ClO2
Correct answer is option 'D'. Can you explain this answer?

Nidhi Tamak answered
Paramagnetic behavior is seen by those who has unpaired electrons that's why option d is correct because it has unpaired electron.

The maximum number of elements present in seventh period of the modern periodic table is:
  • a)
    32
  • b)
    8
  • c)
    2
  • d)
    18
Correct answer is option 'A'. Can you explain this answer?

Anjali Iyer answered
The total number of electrons that can be accommodated in seventh period are 2 ( in 7s) + 14(in 5f) + 10(in 6d )+ 6(in 7p) = 32. The maximum number of elements present in it is 32.

What is the maximum number of electrons that can be filled in 3d subshell?
  • a)
    2
  • b)
    14
  • c)
    6
  • d)
    10
Correct answer is option 'D'. Can you explain this answer?

Shreya Gupta answered
There are 5 orbitals in d subshell  and each orbital can accommodate 2 electrons. Hence maximum number of electrons that can be filled in 3d subshell is 10.

The largest atomic radius among the following is of:
  • a)
    Na
  • b)
    Mg
  • c)
    K
  • d)
    Ca
Correct answer is option 'C'. Can you explain this answer?

Geetika Shah answered
Atomic radius decreases along period, the very next elements K ,Ca has K has higher atomic radius.

Among the following elements element with highest ionisation enthalpy is:
  • a)
    N
  • b)
    C
  • c)
    O
  • d)
    B
Correct answer is option 'A'. Can you explain this answer?

Pooja Shah answered
Among the given molecules, N2 has highest ionization enthalpy.The reason behind is the stability of half-filled orbitals which makes it more stable than other elements in the given option list.

Which of the following elements are called representative elements?
  • a)
    p block elements only
  • b)
    s and p block elements only
  • c)
    d block elements only
  • d)
    s block elements only
Correct answer is option 'B'. Can you explain this answer?

Gaurav Kumar answered
The elements of "s" and "p" blocks except "d" group elements are called as representative elements. Their outer shells are not completely filled with electrons. The elements get the nearest inert gas configuration by losing or gaining or sharing of electrons. 

Inert gases belong to which block of the periodic table?
  • a)
    s-block
  • b)
    d-block
  • c)
    p-block
  • d)
    f-block
Correct answer is 'A'. Can you explain this answer?

Rajeev Saxena answered
The six noble gases are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). Their atomic numbers are, respectively, 2, 10, 18, 36, 54, and 86.

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