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Chemistry · Classification of Elements and Periodicity in Properties
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Chemistry · Classification of Elements and Periodicity in Properties
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Dobereiner's triads were applicable to all known elements without any exception. Reason (R): In Dobereiner's triads, the atomic weight of the middle element was roughly the average of the atomic weights of the first and third elements. In the light of the above statements, choose the correct answer from the options given below:
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Mendeleev left several gaps in his periodic table for undiscovered elements. The elements predicted below aluminum and silicon were respectively designated as:
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Match List-I with List-II: List-I List-II A Shielding/Screening effect I Reduction of effective nuclear charge experienced by valence electrons B Electron gain enthalpy of Oxygen II Less negative than that of Sulfur due to strong interelectronic repulsion in small \( n=2 \) shell C Pauling electronegativity of Fluorine III Assigned an arbitrary value of \( 4.0 \) D Diagonal relationship IV Similarity in properties between diagonally adjacent elements like Li and Mg Choose the correct answer from the options given below:
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What is the maximum covalency of boron due to the availability of only four valence orbitals (\( 2s \) and \( 2p \))?
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In Johann Dobereiner's triads, if the atomic weights of the first and third elements are \( 7 \) and \( 39 \) respectively, what is the predicted atomic weight of the middle element?
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Arrange the following elements in increasing order of their metallic character: \( \text{Si}, \text{Be}, \text{Mg}, \text{Na}, \text{P} \).
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Given below are two statements: Statement I: The atomic radius generally decreases across a period from left to right due to an increase in effective nuclear charge. Statement II: The atomic radius within a group/vertical column decreases regularly with an increase in atomic number. In the light of the above statements, choose the most appropriate answer from the options given below:
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According to the chemical reactions with water given in the text, what are the products formed when \( \text{Na}_2\text{O} \) and \( \text{Cl}_2\text{O}_7 \) react with water respectively?
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Consider the electron addition process \( X(g) + e^- \rightarrow X^-(g) \). Based on Table 3.7 data, which of the following elements has the highest negative electron gain enthalpy (\( \Delta_{eg}H \))?
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Why is the first ionization enthalpy of magnesium greater than that of aluminium?
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Consider the following statements regarding Mendeleev's periodic table: (A) Mendeleev ignored the order of atomic weights in certain instances to group elements with similar properties together. (B) Iodine with a lower atomic weight than tellurium was placed in Group VII along with fluorine, chlorine, and bromine. (C) Mendeleev left gaps for undiscovered elements like eka-aluminium and eka-silicon. (D) Mendeleev's periodic table was published in 1905. How many of the above statements are correct?
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John Alexander Newlands proposed the Law of Octaves in 1865. According to this law, the properties of every eighth element are similar to those of the first element. This relationship was found to be true only up to which element?
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What is the formula of the compound formed between silicon (Group 14) and bromine (Group 17)?
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Given below are two statements: Statement I: Johann Dobereiner in the early 1800's was the first to consider the idea of trends among properties of elements. Statement II: Newlands' Law of Octaves was widely accepted at that time and he was awarded the Davy Medal in 1887 by the Royal Society, London. In the light of the above statements, choose the most appropriate answer from the options given below:
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What is the IUPAC symbol for the element Ununennium (atomic number 119)?
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Given below are two statements: Statement I: The atomic radius generally decreases across a period from left to right due to an increase in effective nuclear charge. Statement II: The atomic radius increases down a group because the principal quantum number (\( n \)) increases and inner core electrons shield the valence electrons. In the light of the above statements, choose the most appropriate answer from the options given below:
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Match List-I with List-II: List-I List-II A Electronegativity of Fluorine I \( 3.0 \) B Electronegativity of Chlorine II \( 4.0 \) C First electron gain enthalpy of Chlorine III \( -328 \text{ kJ mol}^{-1} \) D First electron gain enthalpy of Fluorine IV \( -349 \text{ kJ mol}^{-1} \) Choose the correct answer from the options given below:
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Match List-I (Property / Parameter) with List-II (Periodic Trend Across a Period):
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Which group of elements is known as the chalcogens?
Read answer →Chemistry · Classification of Elements and Periodicity in Properties
Based on Table 3.6(a) for atomic radii across the second period, which element has the largest atomic radius?
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Match List-I with List-II: List-I List-II A Covalent Radius of Chlorine (\( \text{Cl}_2 \)) I \( 186 \text{ pm} \) B Metallic Radius of Sodium II \( 99 \text{ pm} \) C Metallic Radius of Copper III \( 128 \text{ pm} \) D Ionic Radius of Fluoride ion (\( \text{F}^- \)) IV \( 136 \text{ pm} \) Choose the correct answer from the options given below:
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Given below are two statements: Statement I: Lanthanoids and actinoids are placed in separate panels at the bottom of the periodic table. Statement II: The horizontal rows in the periodic table are called groups and vertical columns are called periods. In the light of the above statements, choose the most appropriate answer from the options given below:
Read answer →Chemistry · Classification of Elements and Periodicity in Properties
