Chemistry Quiz Questions And Answers For Class 12

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Chemistry Quiz Questions And Answers For Class 12 - Quiz

Hey, are you looking for an online test of chemistry quiz questions and answers for class 12th students? If so, you have reached the right place. The test contains questions related to every chapter of grade 12 chemistry to make students practice better than ever. From containing questions related to elements and compounds to magnets and paramagnetic substances, the quiz is overall reading material for a student who is looking for a test to examine their knowledge. So, take up this quiz and check how prepared you are for your upcoming exams.


Questions and Answers
  • 1. 

    The ion which has the highest magnetic moment is………

    • A.

      Sc+3

    • B.

      Fe+3

    • C.

      V+2

    • D.

      Cr+4

    Correct Answer
    B. Fe+3
    Explanation
    The ion Fe+3 has the highest magnetic moment because it has an unpaired electron in its d orbital. This unpaired electron allows Fe+3 to have a higher magnetic moment compared to the other ions listed. The other ions do not have unpaired electrons in their d orbitals, so their magnetic moments are lower.

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  • 2. 

    The following compounds are paramagnetic and colored, except…..

    • A.

      FeCl3

    • B.

      CuCl2

    • C.

      ScCl3

    • D.

      CoCl2

    Correct Answer
    C. ScCl3
    Explanation
    ScCl3 is the correct answer because it is not paramagnetic and colored. Paramagnetic compounds contain unpaired electrons, which are attracted to a magnetic field, while colored compounds absorb certain wavelengths of light, resulting in their distinct color. FeCl3 and CoCl2 are both paramagnetic and colored, while CuCl2 is paramagnetic but not colored. ScCl3, on the other hand, does not have any unpaired electrons and therefore is not paramagnetic. Additionally, it does not exhibit any distinct color.

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  • 3. 

    The following figure represents a chemical reaction, (∆H) value for this reaction is……….. [ +50 /-50 ] The activation energy before using catalyst is…….. [ +150 / +100] The activation energy after using catalyst is …….. [ +100 /+50]

    • A.

      -50,+100,+50

    • B.

      +50,+100,+50

    • C.

      -50,+150,+50

    • D.

      +50,+100,+100

    Correct Answer
    A. -50,+100,+50
    Explanation
    The given chemical reaction is represented by the figure. The ∆H value for this reaction is not provided in the question. However, it can be inferred that the activation energy before using the catalyst is +150 and after using the catalyst is +100. This is because the activation energy decreases when a catalyst is used, making it easier for the reaction to occur. The ∆H value and the activation energy after using the catalyst are not provided in the given options. Therefore, the correct answer cannot be determined based on the given information.

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  • 4. 

    In a controlled experiment, when various substances are introduced into a tube with a sensitive balance indicator, which of the following substances induces the most significant movement in the indicator?

    • A.

      V2+

    • B.

      Fe2+

    • C.

      Mn2+

    • D.

      Cr3+

    Correct Answer
    D. Cr3+
    Explanation
    In a controlled experiment involving the introduction of various substances into a tube with a sensitive balance indicator, Cr3+ (Chromium III ion) would likely induce the most significant movement in the indicator. This is because Cr3+ ions typically have a higher charge density compared to ions like V2+ (Vanadium II), Fe2+ (Iron II), and Mn2+ (Manganese II). The higher charge density of Cr3+ results from its three positive charges and smaller ionic radius, which enhances its ability to interact with other molecules and particles in the environment. This stronger interaction can lead to greater influence on the balance indicator, making it move more noticeably.

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  • 5. 

    The following elements are arranged according to chemical activity Iron  Copper  Silver  Platinum If you knew that the element scandium replaces hydrogen of water vigorously, what is its occupying place in the previous arrangement?

    • A.

      After copper

    • B.

      Between iron and copper

    • C.

      After silver

    • D.

      Before iron

    Correct Answer
    D. Before iron
    Explanation
    Scandium, which replaces hydrogen of water vigorously, would have a higher chemical activity than iron. Therefore, it would occupy a place before iron in the previous arrangement of elements arranged according to chemical activity.

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  • 6. 

    1. If you have two solutions, one of them contains V3+ ions and the other contains Zn2+ ions. Which of those solutions is colorless? [ V3+- Zn2+]
    And the scientific reason behind this is that….... [all of its d-electrons are unpaired-all of its d-electrons are paired]

    • A.

      Zn2+, all of its d-electrons are paired

    • B.

      V3+  ,all of its d-electrons are unpaired

    • C.

      Zn2+, all of its d-electrons are unpaired

    • D.

      V3+  ,all of its d-electrons are paired

    Correct Answer
    A. Zn2+, all of its d-electrons are paired
    Explanation
    The correct answer is Zn2+, all of its d-electrons are paired. This is because when all of the d-electrons in an ion are paired, it results in a colorless solution. In contrast, when the d-electrons are unpaired, it can lead to the absorption of certain wavelengths of light, causing the solution to appear colored. In the case of V3+ ions, all of its d-electrons are unpaired, which can result in a colored solution. However, in Zn2+ ions, all of its d-electrons are paired, leading to a colorless solution.

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  • 7. 

    Choose a word to illustrate the following phrase: Two elements of the first transition series each having only one oxidation state.

    • A.

      Scandium and copper

    • B.

      Scandium and zinc

    • C.

      Zinc and nickel

    • D.

      Copper and chromium

    Correct Answer
    B. Scandium and zinc
    Explanation
    Scandium and zinc are the correct answer because they are the only two elements in the first transition series that have only one oxidation state. Scandium has an oxidation state of +3, while zinc has an oxidation state of +2. The other options, copper, nickel, and chromium, all have multiple oxidation states.

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  • 8. 

    When the d-sublevel contains eight electrons, the number of half-filled orbitals equals….....

    • A.

      1

    • B.

      2

    • C.

      3

    • D.

      4

    Correct Answer
    B. 2
    Explanation
     When the d-sublevel contains ten electrons, it means that all five d orbitals are filled with two electrons each. When the d sublevel contains eight electrons, four orbitals are filled with two electrons each.

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  • 9. 

    The compound FeCl2 is…….

    • A.

      Paramagnetic and colored

    • B.

      Diamagnetic and colorless

    • C.

      Paramagnetic and colorless

    • D.

      Diamagnetic and colored

    Correct Answer
    A. Paramagnetic and colored
    Explanation
    FeCl2 is paramagnetic because it contains unpaired electrons. Paramagnetic substances are attracted to a magnetic field due to the presence of unpaired electrons. It is also colored because the presence of unpaired electrons allows for absorption and emission of specific wavelengths of light, resulting in a visible color.

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  • 10. 

    What is the name of the element or compound used in detecting of some industrials flaws as cracks in welded locations?

    • A.

      Copper

    • B.

      Vanadium pentoxide

    • C.

      Cobalt-60

    • D.

      Copper (II) sulphate

    Correct Answer
    C. Cobalt-60
    Explanation
    Cobalt-60 is used in the detection of industrial flaws such as cracks in welded locations. This radioactive isotope emits gamma rays, which can penetrate through materials and reveal hidden flaws. By exposing the welded area to Cobalt-60, any cracks or defects can be detected through the analysis of the gamma rays that are emitted and detected.

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  • 11. 

    The element where the d or f sublevel is completely fille with electrons either in the atomic state or oxidation state is…..

    • A.

      Main transition element

    • B.

      Non- transition element

    • C.

      Inner transition element

    • D.

      None of the above

    Correct Answer
    B. Non- transition element
    Explanation
    The correct answer is Non-transition element. Non-transition elements refer to elements in which the d or f sublevel is not completely filled with electrons in either the atomic state or the oxidation state. Transition elements, on the other hand, have partially filled d or f sublevels. Inner transition elements are a subset of transition elements and are located at the bottom of the periodic table. Therefore, the element where the d or f sublevel is completely filled with electrons would not be a non-transition element.

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  • 12. 

    An element belongs to the first transition series, it’s magnetic moment in X2O3 compound equals 3, deduce the atomic number of this element

    • A.

      21

    • B.

      22

    • C.

      23

    • D.

      24

    • E.

      25

    • F.

      26

    Correct Answer
    D. 24
    Explanation
    The atomic number of an element determines the number of protons in its nucleus. In the first transition series, the elements have atomic numbers ranging from 21 to 30. The magnetic moment in X2O3 compound equals 3 indicates that the element has three unpaired electrons. Based on the electron configuration of transition metals, an element with three unpaired electrons would have an atomic number of 24, which corresponds to chromium (Cr). Therefore, the correct answer is 24.

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  • 13. 

    What is the name of the alloy used in avoiding corrosion and rusting of soft drinks cans?

    • A.

      Ferromanganese alloy

    • B.

      Ferrochrome alloy

    • C.

      Aluminum-manganese alloy

    • D.

      Nickel-chrome alloy

    Correct Answer
    C. Aluminum-manganese alloy
    Explanation
    Aluminum-manganese alloy is used in soft drink cans to prevent corrosion and rusting. This alloy has a high resistance to corrosion and forms a protective oxide layer on the surface of the can, preventing any reaction with the contents of the can. It is a commonly used alloy in the packaging industry due to its durability and ability to maintain the quality of the product inside the can.

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  • 14. 

    The following is a modified true / false question. In it, you must decide if each individual statement is true (T) or false (F). If both are true, then you must also decide if the second statement is a correct explanation (CE) of the first statement. Examples: EX.1: H2SO4 is a strong acid because  H2SO4 contains sulphur. EX.2: An atom of oxygen is electrically neutral because an oxygen atom contains an equal number of protons &electrons. Answers: EX.1: T, T EX.2: T, T, C.E Question: When a chlorine atom gains an electron, it becomes a positively charged ion. A neutral atom has equal numbers of protons and electrons.

    • A.

      T,T

    • B.

      T,T,C.E

    • C.

      T,F

    • D.

      F,T

    • E.

      F,F

    Correct Answer
    D. F,T
    Explanation
    An acid is strong when it easily loses a proton in solution. When a chlorine atom gains an electron, it does not become a positively charged ion. This is because when an atom gains an electron, it becomes negatively charged, not positively charged. However, it is true that a neutral atom has equal numbers of protons and electrons

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  • 15. 

    Determine the ions which can’t be produced by normal chemical reactions from the following: 1) Sc2+   2)Mn4+    3) Co2+    4)Zn+

    • A.

      1 and 2

    • B.

      1 and 3

    • C.

      2 and 3

    • D.

      3 and 4

    • E.

      1 and 4

    Correct Answer
    E. 1 and 4
    Explanation
    The ions that cannot be produced by normal chemical reactions are Sc2+ and Zn+. Scandium (Sc) typically forms a +3 ion, not a +2 ion. Zinc (Zn) typically forms a +2 ion, not a +1 ion. Therefore, Sc2+ and Zn+ cannot be produced by normal chemical reactions.

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  • 16. 

    Magnetic moment is…..

    • A.

      The tendency of an element to be attracted to an external magnet

    • B.

      Determined by the number of unpaired electrons in the 3d sublevel

    • C.

      Determined by the number of paired electrons in the 3d sublevel

    • D.

      A&b

    • E.

      A&c

    Correct Answer
    D. A&b
    Explanation
    The magnetic moment of an element is determined by the number of unpaired electrons in the 3d sublevel and is described by the attraction of a compound to a magnet. This means that if an element has unpaired electrons, it will have a magnetic moment and will be attracted to an external magnet. Therefore, the correct answer is a. The presence of unpaired electrons in the 3d sublevel is a key factor in determining the magnetic properties of an element.

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  • 17. 

    Manganese (II) ion is …….. oxidized to manganese (III) ion

    • A.

      Easily

    • B.

      Difficultly

    • C.

      Not possible

    • D.

      No correct answer

    Correct Answer
    B. Difficultly
    Explanation
    The given statement suggests that the oxidation of Manganese (II) ion to Manganese (III) ion is not an easy process but rather a difficult one. This implies that it requires a significant amount of energy or specific conditions for this oxidation reaction to occur. Therefore, the correct answer is "Difficultly".

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  • 18. 

    You have similar rods of the following elements Ti, Ni, Cu, Fe Which has the highest ability to conduct electricity?

    • A.

      Ti

    • B.

      Ni

    • C.

      Cu

    • D.

      Fe

    Correct Answer
    C. Cu
    Explanation
    Copper (Cu) has the highest ability to conduct electricity among the given elements. This is because copper has a high electrical conductivity due to its atomic structure. It has a large number of free electrons in its outermost energy level, which allows for easy movement of electric charge. On the other hand, titanium (Ti), nickel (Ni), and iron (Fe) have lower electrical conductivity compared to copper.

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  • 19. 

    All of the transition metals are characterized by……….

    • A.

      Several oxidation states

    • B.

      Forming colored solutions

    • C.

      Electric conductivity

    • D.

      Ability to be magnetized

    Correct Answer
    C. Electric conductivity
    Explanation
    Transition metals are characterized by their ability to conduct electricity. This is due to the presence of free electrons in their outermost energy level, which can move freely and carry an electric current. This property is not commonly found in other elements, making it a distinguishing feature of transition metals.

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  • 20. 

    What is the name of the compound or element used in determining the percentage of sugar in urine of diabetic patients?

    • A.

      Iron

    • B.

      Vanadium pentoxide

    • C.

      Manganese

    • D.

      Copper(II) sulphate

    Correct Answer
    D. Copper(II) sulphate
    Explanation
    Copper(II) sulphate is used in determining the percentage of sugar in urine of diabetic patients. It is commonly used in a test called Benedict's test, which is used to detect the presence of reducing sugars such as glucose in a solution. When heated with a reducing sugar, copper(II) sulphate is reduced to copper(I) oxide, resulting in a color change from blue to green, yellow, or red, depending on the amount of sugar present. This color change is then used to determine the percentage of sugar in the urine sample.

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  • 21. 

    …… is a transition element in the first transition series that has an oxidation number higher than its vertical group number oxidation state.

    • A.

      Copper

    • B.

      Iron

    • C.

      Cobalt

    • D.

      Scandium

    • E.

      Silver

    Correct Answer
    A. Copper
    Explanation
    Copper is a transition element in the first transition series that has an oxidation number higher than its vertical group number. In the first transition series, the vertical group number represents the maximum oxidation state that an element can have. Copper, however, can have an oxidation state of +2 or +1, which is higher than its group number of +1. This is due to the presence of partially filled d-orbitals in its electron configuration, allowing for different oxidation states.

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  • 22. 

    What is the name of the element or compound used in getting pure drinking water in desert locations?

    • A.

      Cobalt

    • B.

      Vanadium pentoxide

    • C.

      Nickel

    • D.

      Copper(II) sulphate

    • E.

      Titanium dioxide

    • F.

      Titanium dioxide

    Correct Answer
    D. Copper(II) sulphate
    Explanation
    Copper(II) sulphate is used in getting pure drinking water in desert locations. It acts as a disinfectant and helps in killing harmful bacteria and algae in water. Copper(II) sulphate also aids in removing impurities and improving the taste of water. It is commonly used in water treatment processes to ensure the safety and quality of drinking water in arid regions.

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  • 23. 

    Why is it easy to convert titanium(III) ion to titanium (IV) ion? Because titanium (III) ion is…….

    • A.

      Easily oxidized by losing electrons

    • B.

      Easily oxidized by gaining electrons

    • C.

      Easily reduced by losing electrons

    • D.

      Easily reduced by gaining electrons

    Correct Answer
    A. Easily oxidized by losing electrons
    Explanation
    Titanium (III) ion has a lower oxidation state compared to titanium (IV) ion. This means that titanium (III) ion has a greater tendency to lose electrons and be oxidized. Therefore, it is easy to convert titanium (III) ion to titanium (IV) ion by oxidizing it through the loss of electrons.

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  • 24. 

    The process used to convert hydrogen and carbon monoxide gases into liquid fuel is…

    • A.

      Contact process

    • B.

      Fischer-Tropsch method

    • C.

      Haber-Bosch method

    • D.

      Hydrogenation

    Correct Answer
    B. Fischer-Tropsch method
    Explanation
    This method involves the catalytic conversion of carbon monoxide and hydrogen into hydrocarbons. It was developed in the early 20th century by Franz Fischer and Hans Tropsch and is commonly used in the production of synthetic fuels from coal, natural gas, or biomass. The process allows for the production of a wide range of liquid hydrocarbons, including gasoline, diesel, and jet fuel, making it a versatile and important method in the fuel industry.

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  • 25. 

    Regarding the elements of the first transition, all of the following is correct except….

    • A.

      The atomic mass increases with the increase in atomic number

    • B.

      The density increases as the atomic mass increases

    • C.

      As the atomic number increases it is difficult to be oxidized

    • D.

      The ionization energy decreases with the increase in atomic number

    Correct Answer
    D. The ionization energy decreases with the increase in atomic number
    Explanation
    As the atomic number increases, the ionization energy generally increases. This is because as the atomic number increases, the number of protons in the nucleus also increases, resulting in a stronger attraction between the nucleus and the electrons. This stronger attraction makes it more difficult to remove an electron from the atom, hence increasing the ionization energy. Therefore, the statement that the ionization energy decreases with the increase in atomic number is incorrect.

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  • 26. 

    Choose the symbol of a transition element whose magnetic moment in its atomic state and its oxidation state (+2) equal 5

    • A.

      Sc

    • B.

      Ti

    • C.

      V

    • D.

      Cr

    • E.

      Mn

    • F.

      Fe

    • G.

      Co

    • H.

      Ni

    • I.

      Cu

    Correct Answer
    E. Mn
    Explanation
    In the given question, we are asked to choose the symbol of a transition element whose magnetic moment in its atomic state and its oxidation state (+2) equal 5. The magnetic moment of an atom is determined by the number of unpaired electrons. In the case of Mn, it has 5 unpaired electrons in its atomic state and when it is in the +2 oxidation state, it still retains 5 unpaired electrons. Therefore, Mn is the correct answer as it satisfies the given condition.

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  • 27. 

    Which one of the following transition elements has the highest 1st ionization potential?

    • A.

      Ni  ------> Ni+

    • B.

      V ------> V+

    • C.

      Sc ------> Sc+

    • D.

      Ti ------> Ti+

    Correct Answer
    A. Ni  ------> Ni+
    Explanation
    The first ionization potential is the energy required to remove one electron from an atom in its gaseous state. It is a measure of how tightly the electrons are held by the nucleus. As we move across a period from left to right in the periodic table, the atomic radius decreases and the effective nuclear charge increases, making it more difficult to remove an electron. Nickel (Ni) is located towards the right side of the transition metal series, so it has a higher effective nuclear charge compared to the other elements listed. Therefore, it requires more energy to remove an electron from Ni, making it have the highest 1st ionization potential among the given options.

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  • 28. 

    X,Y,Z,L represent four transition elements and their oxides are X2O5, Y2O3, ZO2, L2O, the right arrangement of their oxidation number in these oxides is…..

    • A.

      L<Y<Z<X

    • B.

      L<Z<Y<X

    • C.

      Y<L<Z<X

    • D.

      L<Y<X<Z

    Correct Answer
    A. L<Y<Z<X
    Explanation
    The correct arrangement of the oxidation numbers in these oxides is L

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  • 29. 

    Which of the following chemical formula represents a non-existent compound

    • A.

      TiO2

    • B.

      Co2O3

    • C.

      NiO

    • D.

      Zn2O3

    Correct Answer
    D. Zn2O3
    Explanation
    All the given chemical formulas represent real compounds except for Zn2O3. Zn2O3 does not exist in nature or in any known chemical database.

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  • 30. 

    Which element in the first transition series is expected to have the highest ionization energy?

    • A.

      Scandium

    • B.

      Titanium

    • C.

      Vanadium

    • D.

      Zinc

    Correct Answer
    D. Zinc
    Explanation
    In the case of zinc (Zn), it has a filled d-subshell (3d10) after losing its two outermost electrons (4s2), resulting in a more stable electron configuration. This filled d-subshell imparts extra stability, making it more difficult to remove an electron. As a result, zinc tends to have a higher ionization energy compared to elements like Scandium, Titanium, and Vanadium in the first transition series.

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Zohra Sattar |PhD, Chemistry |
Chemistry Expert
Dr. Zohra Sattar Waxali earned her doctorate in chemistry and biochemistry from Northwestern University, specializing in the metallomes of cardiac cells and stem cells, and their impact on biological function. Her research encompasses the development of arsenoplatin chemotherapeutics, stapled peptide estrogen receptor inhibitors, and antimicrobial natural products. With her expertise, Dr. Waxali ensures the accuracy and relevance of our chemistry quizzes, contributing to a comprehensive understanding of chemical principles and advancements in the field.

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  • Apr 29, 2024
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