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All questions of Halogens for SSS 2 Exam

In the MOT of F2 molecule, number of electrons occupying antibonding orbitals are
    Correct answer is '8'. Can you explain this answer?

    Nandita Ahuja answered
    Fluorine atom have 2+7 electrons so an F2 molecule contain 18 electrons.

    Hence, 8 electrons occupy the antibonding orbitals.

    When chlorine reacts with hot, cone. NaOH, the products formed are
    • a)
      NaCI
    • b)
      NaOCI
    • c)
      NaCIO3
    • d)
      HCI
    Correct answer is option 'A,C'. Can you explain this answer?

    Anupama Nair answered
    When Cl2 reacts with hot and concentrated NaOH, then....6NaOH+3Cl2→5NaCl +NaClO3+3H2O...When Cl2 reacts with cold and dilute NaOH then ...2NaOH+Cl2→NaCl+NaOCl+H2O

    Mixture which contains equal amount of sodium chloride (NaCl) and sodium chlorate (NaClO3) gives off
    • a)
      bleach
    • b)
      aerosols
    • c)
      solvents
    • d)
      refrigerants
    Correct answer is option 'A'. Can you explain this answer?

    Om Desai answered
    The correct answer is option A
    On decomposition of NaClO3 , it gives NaCl and O in nascent form. it might get decomposed. As we know nascent [O] shows bleaching action due to its oxidizing properties.

    Correct order of bond angles are in 
    • a)
      H2O > OF2 > Cl2O > CIO2
    • b)
      CIO2 > Cl2O > H2O > OF2 
    • c)
      OF2 > H2O > Cl2O > ClO2
    • d)
      OF2 > OCI2 > H2O > CIO2
    Correct answer is option 'B'. Can you explain this answer?

    In CIO2, due to larger size of chlorine atom, repulsion between non-bonding electrons on the chlorine atoms overcome the lone pair-lone pair repulsion. Hence, the order of bond angle 
    CIO2 > Cl2O > H2O > OF2

    When carnallite is dissolved in water the number of ions formed are
      Correct answer is '5'. Can you explain this answer?

      Carnallite is a double salt. It will dissociate into simple substances or ions completely when dissolved in water.

      Hence, 5 ions are produced.

      Which of the following arrangements gives the correct order of increasing oxidation number of iodine?
      • a)
        I2 < HI < ICI < HIO4
      • b)
        HI < ICI < I2 < HIO4
      • c)
        ICI < HI < HIO4< I2
      • d)
        HI < I2< ICI < HIO4
      Correct answer is option 'D'. Can you explain this answer?

      Preethi Kaur answered
      Correct answer: Option D

      To determine the correct order of increasing oxidation number of iodine in the given arrangements, we need to understand the concept of oxidation numbers and how they change in different compounds.

      Oxidation number is the hypothetical charge that an atom would have if all bonds in a compound were 100% ionic. It is a useful tool for keeping track of electron transfers during chemical reactions.

      In the given arrangements, we have the following compounds:

      a) I2, HI, ICI, HIO4
      b) HI, ICI, I2, HIO4
      c) ICI, HI, HIO4, I2
      d) HI, I2, ICI, HIO4

      Explanation:

      In order to determine the oxidation number of iodine in each compound, we need to consider the following rules:

      1. The oxidation number of a free element is always zero.
      2. The oxidation number of a monatomic ion is equal to its charge.
      3. In compounds, the oxidation number of hydrogen is usually +1, and the oxidation number of oxygen is usually -2.
      4. The sum of the oxidation numbers in a neutral compound is zero, and it is equal to the charge of the compound in an ion.

      Now, let's analyze each compound in the given arrangements and determine the oxidation number of iodine:

      a) I2: The oxidation number of a free element is always zero.
      HI: Hydrogen usually has an oxidation number of +1.
      ICI: Since the total oxidation number of a compound is zero, and hydrogen has an oxidation number of +1, we can deduce that iodine in ICI has an oxidation number of +1.
      HIO4: Oxygen usually has an oxidation number of -2, and since the total oxidation number of the compound is zero, iodine in HIO4 has an oxidation number of +7.

      b) HI: Hydrogen usually has an oxidation number of +1.
      ICI: Since the total oxidation number of a compound is zero, and hydrogen has an oxidation number of +1, we can deduce that iodine in ICI has an oxidation number of +1.
      I2: The oxidation number of a free element is always zero.
      HIO4: Oxygen usually has an oxidation number of -2, and since the total oxidation number of the compound is zero, iodine in HIO4 has an oxidation number of +7.

      c) ICI: Since the total oxidation number of a compound is zero, and hydrogen has an oxidation number of +1, we can deduce that iodine in ICI has an oxidation number of +1.
      HI: Hydrogen usually has an oxidation number of +1.
      HIO4: Oxygen usually has an oxidation number of -2, and since the total oxidation number of the compound is zero, iodine in HIO4 has an oxidation number of +7.
      I2: The oxidation number of a free element is always zero.

      d) HI: Hydrogen usually has an oxidation number of +1.
      I2: The oxidation number of a free element is always zero.
      ICI: Since the total oxidation number of a compound is zero, and hydrogen has an oxidation number of +1, we can deduce that iodine in ICI has an oxidation number of +1.

      Direction (Q. Nos. 1-10) This section contains 10 multiple choice questions. Each question has four choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
      Q. 
      Which of the following is not a pseudo halideion?
      • a)
        CNO-
      • b)
        CN-
      • c)
        SCN-
      • d)
        S2-
      Correct answer is option 'D'. Can you explain this answer?

      Rutuja Ahuja answered
      Explanation:

      Pseudo halides are ions that have similar chemical properties to halide ions (such as chloride, bromide, and iodide) but are not actually halides. They typically have a negative charge and contain a central atom bonded to one or more electronegative atoms.

      In the given options, CNO-, CN-, and SCN- are all examples of pseudo halide ions because they exhibit similar chemical properties to halides. However, S2- is not a pseudo halide ion.

      The reason S2- is not a pseudo halide ion is because it does not have similar chemical properties to halide ions. Unlike halides, which are typically good nucleophiles and are often used in substitution reactions, S2- is a strong reducing agent and is not commonly involved in substitution reactions.

      S2- is a reducing agent because it can easily gain two electrons to form S2-, which has a filled valence shell. This makes it a good reducing agent in redox reactions. In contrast, halides are not strong reducing agents because they have a filled valence shell and do not readily gain electrons.

      Additionally, S2- does not have the same size or electronegativity as halide ions. Halides (such as Cl-, Br-, and I-) have larger atomic radii and lower electronegativities than sulfur (S). This difference in size and electronegativity affects their chemical properties and reactivity.

      In summary, S2- is not a pseudo halide ion because it does not exhibit the same chemical properties as halide ions and has different size and electronegativity characteristics.

      The stability of interhalogen compounds follows the order
      • a)
        IF3 > BrF3 > CIF3
      • b)
        BrF3 > IF3 > CIF3
      • c)
        CIF3 > BrF3 > IF3
      • d)
        CIF3 > IF3 > BrF3
      Correct answer is option 'A'. Can you explain this answer?

      Electropositive character of halogens is in order I > Br > Cl . Central atom is bigger in size, more electropositive nature form stable interhalogen compound.

      The source of iodine is
      • a)
        in free state
      • b)
        in seaweeds
      • c)
        as caliche
      • d)
        As Agl
      Correct answer is option 'B,C'. Can you explain this answer?

      Certain deep seaweeds contain 0.5% of iodine in their ashes. Caliche or crude chile saltpetre contain about 0.2% of NaIO3.

      In perchloric acid (HCIO4), the number of σ and π-bonds
      • a)
        5σ and 4π-bonds
      • b)
        6σ and 3π-bonds
      • c)
        5σ and 3π-bonds
      • d)
        5σ and 2π-bonds
      Correct answer is option 'C'. Can you explain this answer?

      Maya Reddy answered

      Perchloric Acid (HCIO4)

      Perchloric acid (HCIO4) is a strong acid with the chemical formula HClO4. It is a colorless, odorless, and highly corrosive liquid.

      Number of O and Cl bonds

      - In perchloric acid (HCIO4), there are 5 oxygen (O) atoms bonded to the central chlorine (Cl) atom.
      - These oxygen atoms are connected to the central chlorine atom through single bonds, resulting in a total of 5 single bonds (O-Cl).

      - There are also 3 oxygen atoms in perchloric acid that are not directly bonded to the central chlorine atom. These oxygen atoms are connected to each other through single bonds, resulting in a total of 3 single bonds (O-O).

      Therefore, the correct answer is option C, which states that there are 5 O-Cl bonds and 3 O-O bonds in perchloric acid (HCIO4).

      In chlorination of water, reactive oxygen atoms are produced by
      • a)
        Cl2 + H2O
      • b)
        H2CO3
      • c)
        HClO
      • d)
        H2ClO2
      Correct answer is option 'C'. Can you explain this answer?

      Preethi Kaur answered
      Reactive oxygen atoms are produced during the chlorination of water. This process involves the addition of chlorine gas (Cl2) to water (H2O) to disinfect it and kill harmful bacteria and microorganisms. The reaction is as follows:

      Cl2 + H2O -> HCl + HClO

      In this reaction, chlorine gas reacts with water to form hydrochloric acid (HCl) and hypochlorous acid (HClO). It is the hypochlorous acid that produces reactive oxygen atoms.

      Explanation:

      1. Chlorine gas (Cl2):
      Chlorine gas is introduced into water to kill bacteria and microorganisms. It is a powerful disinfectant and reacts with water to form hydrochloric acid and hypochlorous acid.

      2. Water (H2O):
      Water is the medium in which the chlorination process takes place. It is the reactant that reacts with chlorine gas to form hydrochloric acid and hypochlorous acid.

      3. Hydrochloric acid (HCl):
      Hydrochloric acid is formed during the reaction between chlorine gas and water. It is a strong acid and has disinfectant properties. However, it does not produce reactive oxygen atoms.

      4. Hypochlorous acid (HClO):
      Hypochlorous acid is the primary product of the chlorination reaction. It is a weak acid and has powerful disinfectant properties. It is also responsible for producing reactive oxygen atoms.

      5. Reactive oxygen atoms:
      Hypochlorous acid (HClO) can undergo a process called disassociation, where it breaks down into reactive oxygen atoms. These reactive oxygen atoms are highly reactive and can attack and destroy organic matter, including bacteria and microorganisms.

      In conclusion, during the chlorination of water, reactive oxygen atoms are produced by the disassociation of hypochlorous acid (HClO), which is formed when chlorine gas reacts with water. These reactive oxygen atoms play a crucial role in disinfecting water and killing harmful bacteria and microorganisms.

      In the known interhalogen compounds, the maximum number of atoms are
      • a)
        4
      • b)
        5
      • c)
        8
      • d)
        7
      Correct answer is option 'C'. Can you explain this answer?

      In IF7, iodine is the least electronegative halogen, so its higher oxidation number (+7) is more stable than those of the lighter member of the group. So clearly there are a total of 8 atoms

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