An element A of group1 shows similarity to an element B belonging to group 2. If A has maximum hydration enthalpy in group 1 then B is:
- Mg
- Be
- Ca
- Sr
The Correct Option is A
Solution and Explanation
The correct answer is (A): Mg
Lithium belongs to group-1, which has maximum hydration enthalpy among the group-1 elements.
Lithium shows diagonal relationship with Mg.
Top JEE Main Chemistry Questions
- MnO₄²⁻, in acidic medium, disproportionates to:
- JEE Main - 2026
- Chemistry
- Redox reactions
The wavelength of spectral line obtained in the spectrum of Li$^{2+}$ ion, when the transition takes place between two levels whose sum is 4 and difference is 2, is
- JEE Main - 2026
- Chemistry
- Atomic Structure
- Consider a mixture $X$ which is made by dissolving $0.4$ mol of $[\mathrm{Co(NH_3)_5SO_4}]Br$ and $0.4$ mol of $[\mathrm{Co(NH_3)_5Br}]SO_4$ in water to make $4$ L of solution. When $2$ L of mixture $X$ is allowed to react with excess $\mathrm{AgNO_3}$, it forms precipitate $Y$. The rest $2$ L of mixture $X$ reacts with excess $\mathrm{BaCl_2}$ to form precipitate $Z$. Which of the following statements is CORRECT?
- JEE Main - 2026
- Chemistry
- coordination compounds
Structures of four disaccharides are given below. Among the given disaccharides, the non-reducing sugar is:
- JEE Main - 2026
- Chemistry
- General Chemistry
The temperature at which the rate constants of the given below two gaseous reactions become equal is ____________ K (Nearest integer).
\[ X \longrightarrow Y, \qquad k_1 = 10^{6} e^{-\frac{30000}{T}} \] \[ P \longrightarrow Q, \qquad k_2 = 10^{4} e^{-\frac{24000}{T}} \] Given: \( \ln 10 = 2.303 \)- JEE Main - 2026
- Chemistry
- Chemical Kinetics
Top JEE Main Enthalpy change Questions
- The group 14 elements A and B have the first ionisation enthalpy values of 708 and 715 kJ mol$^{-1}$ respectively. The above values are lowest among their group members. The nature of their ions A$^{2+}$ and B$^{4+}$ respectively is:
- JEE Main - 2025
- Chemistry
- Enthalpy change
- The incorrect relationship in the following pairs in relation to ionisation enthalpies is:
- JEE Main - 2025
- Chemistry
- Enthalpy change
- Given below are two statements:
Statement (I): The radius of isoelectronic species increases in the order: \[ \text{Mg}^{2+} < \text{Na}^{+} < \text{F}^{-} < \text{O}^{2-} \] Statement (II): The magnitude of electron gain enthalpy of halogens decreases in the order: \[ \text{Cl} > \text{F} > \text{Br} > \text{I} \] In light of the above statements, choose the most appropriate answer from the options given below:- JEE Main - 2025
- Chemistry
- Enthalpy change
- Consider the following cases of standard enthalpy of reaction (\( \Delta H_f^\circ \) in kJ mol\(^{-1}\)): \[ \text{C}_2\text{H}_6(g) + 7 \text{O}_2(g) \rightarrow 2 \text{CO}_2(g) + 3 \text{H}_2\text{O}(l) \quad \Delta H_1^\circ = -1550 \] \[ \text{C(graphite)} + \text{O}_2(g) \rightarrow \text{CO}_2(g) \quad \Delta H_2^\circ = -393.5 \] \[ \text{H}_2(g) + \frac{1}{2} \text{O}_2(g) \rightarrow \text{H}_2\text{O}(g) \quad \Delta H_3^\circ = -286 \] The magnitude of \( \Delta H_f^\circ \) of \( \text{C}_2\text{H}_6(g) \) is \(\_\_\_\_\_\) kJ mol\(^{-1}\) (Nearest integer).
- JEE Main - 2025
- Chemistry
- Enthalpy change
- JEE Main - 2024
- Chemistry
- Enthalpy change
Top JEE Main Questions
- MnO₄²⁻, in acidic medium, disproportionates to:
- JEE Main - 2026
- Redox reactions
- Consider a mixture $X$ which is made by dissolving $0.4$ mol of $[\mathrm{Co(NH_3)_5SO_4}]Br$ and $0.4$ mol of $[\mathrm{Co(NH_3)_5Br}]SO_4$ in water to make $4$ L of solution. When $2$ L of mixture $X$ is allowed to react with excess $\mathrm{AgNO_3}$, it forms precipitate $Y$. The rest $2$ L of mixture $X$ reacts with excess $\mathrm{BaCl_2}$ to form precipitate $Z$. Which of the following statements is CORRECT?
- JEE Main - 2026
- coordination compounds
The wavelength of spectral line obtained in the spectrum of Li$^{2+}$ ion, when the transition takes place between two levels whose sum is 4 and difference is 2, is
- JEE Main - 2026
- Atomic Structure
Identify the correct truth table of the given logic circuit.
- JEE Main - 2026
- communication systems
- Let $z=(1+i)(1+2i)(1+3i)\cdots(1+ni)$, where $i=\sqrt{-1}$. If $|z|^2=44200$, then $n$ is equal to
- JEE Main - 2026
- Complex Numbers and Quadratic Equations
Concepts Used:
Enthalpy change
Enthalpy Change refers to the difference between the heat content of the initial and final state of the reaction. Change in enthalpy can prove to be of great importance to find whether the reaction is exothermic or endothermic.
Formula for change in enthalpy is:-
dH = dU + d(PV)
The above equation can be written in the terms of initial and final states of the system which is defined below:
UF – UI = qP –p(VF – VI)
Or qP = (UF + pVF) – (UI + pVI)
Enthalpy (H) can be written as H= U + PV. Putting the value in the above equation, we obtained:
qP = HF – HI = ∆H
Hence, change in enthalpy ∆H = qP, referred to as the heat consumed at a constant pressure by the system. At constant pressure, we can also write,
∆H = ∆U + p∆V
Standard Enthalpy of Reaction
To specify the standard enthalpy of any reaction, it is calculated when all the components participating in the reaction i.e., the reactants and the products are in their standard form. Therefore the standard enthalpy of reaction is the enthalpy change that occurs in a system when a matter is transformed by a chemical reaction under standard conditions.