COMEDK 2025 Afternoon Shift | Periodic Table and Periodicity Question 1 | Chemistry

The first ionisation enthalpy of Al in $\mathrm{kJ} \mathrm{mol}^{-1}$ is: [Given the first ionisation enthalpy of $\mathrm{Na}, \mathrm{Mg}$ and Si in $\mathrm{kJ} \mathrm{mol}^{-1}$ are 497,738 and 787 respectively]

769

578

488

857

COMEDK 2024 Evening Shift

MCQ (Single Correct Answer)

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With reference to Pauling's Electronegativity scale, which one of the following options shows the correct order of electronegativity values of elements?

$$\mathrm{Na}>\mathrm{Cs}>\mathrm{K}$$

$$\mathrm{Mg}>\mathrm{Al}>\mathrm{Si}$$

$$\mathrm{B}>\mathrm{C}>\mathrm{Al}$$

$$\mathrm{N}>\mathrm{S}>\mathrm{P}$$

COMEDK 2024 Afternoon Shift

MCQ (Single Correct Answer)

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Among the following, which is not according to the property indicated against it?

$$ \mathrm{Mg}^{2+}<\mathrm{Na}^{+}<\mathrm{F}^{-}<\mathrm{O}^{2-} \text { [Increasing Ionic Size] } $$

$$ \mathrm{I}<\mathrm{Br}<\mathrm{F}<\mathrm{Cl} \text { [Increasing Elecrtron Gain Enthalpy with negative sign] } $$

$$ \mathrm{Na}<\mathrm{K}<\mathrm{Rb}<\mathrm{Cs} \text { [Increasing Metallic Radii] } $$

$$ \mathrm{B}<\mathrm{C}<\mathrm{N}<\mathrm{O} \text { [Increasing First Ionisation Enthalpy] } $$

COMEDK 2023 Morning Shift

MCQ (Single Correct Answer)

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The correct decreasing order of negative electron gain enthalpy for $$\mathrm{C}, \mathrm{Ca}, \mathrm{Al}, \mathrm{F}$$ and $$\mathrm{O}$$ is

$$\mathrm{F}>\mathrm{O}>\mathrm{C}>\mathrm{Al}>\mathrm{Ca}$$

$$\mathrm{Ca}>\mathrm{Al}>\mathrm{O}>\mathrm{F}>\mathrm{C}$$

$$\mathrm{Al}>\mathrm{F}>\mathrm{Ca}>\mathrm{C}>\mathrm{O}$$

$$\mathrm{F}>\mathrm{C}>\mathrm{O}>\mathrm{Ca}>\mathrm{Al}$$

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