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Chemistry · EQUILIBRIUM
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1516 questions
Chemistry · THERMODYNAMICS
At 298 K, 18 g of liquid water evaporates into steam. Given \( \Delta_{\text{vap}}H^\ominus = 44.01\text{ kJ mol}^{-1} \) and \( R = 8.314\text{ J K}^{-1}\text{mol}^{-1} \), the internal energy of vaporisation (\( \Delta_{\text{vap}}U^\ominus \)) is approximately:
Read answer →Chemistry · PYQ NEET UG 2019(1)
The compound that is most difficult to protonate is _________.
Read answer →Chemistry · Structure of atom
Consider the following statements about quantum rules and orbitals:\n(A) The principal quantum number \( n \) defines the main shell and size of the orbital.\n(B) For a given value of \( n \), there are \( n \) allowed values of \( l \).\n(C) The number of \( m_l \) values for a given \( l \) is \( 2l + 1 \).\n(D) The total number of electrons in a given subshell is \( 2l + 1 \). \nWhich of the above statements are correct?
Read answer →Chemistry · EQUILIBRIUM
For a 0.10 M aqueous solution of a diprotic acid \( \text{H}_2\text{X} \), the ionization constants are \( K_{a_1} = 4.0 \times 10^{-5} \) and \( K_{a_2} = 1.6 \times 10^{-11} \). The concentration of divalent anion \( [\text{X}^{2-}] \) at equilibrium is:
Read answer →Chemistry · THERMODYNAMICS
Which of the following substances has a standard molar enthalpy of formation (\( \Delta_f H^\ominus \)) equal to zero at 298 K and 1 bar by convention?
Read answer →Chemistry · Classification of Elements and Periodicity in Properties
What is the sign of ionization enthalpy for the removal of an electron from a gaseous atom?
Read answer →Chemistry · THERMODYNAMICS
For the reaction \( 4\text{Fe}(s) + 3\text{O}_2(g) \rightarrow 2\text{Fe}_2\text{O}_3(s) \) at \( 298\text{ K} \), \( \Delta_r H^\circ = -1648\text{ kJ mol}^{-1} \) and \( \Delta_r S^\circ = -549.4\text{ J K}^{-1}\text{mol}^{-1} \). What is the total entropy change \( \Delta S_{\text{total}} \)?
Read answer →Chemistry · CHEMICAL BONDING AND MOLECULAR STRUCTURE
Consider the following statements regarding hybridization and orbital characteristics: (A) Hybrid orbitals are always equivalent in energy and shape. (B) Promotion of an electron is an essential condition prior to hybridization. (C) A \( \pi \) bond is stronger than a \( \sigma \) bond because of greater extent of orbital overlap. (D) Only half-filled orbitals of valence shell take part in hybridization; fully filled orbitals can never participate. Which of the above statements is/are correct?
Read answer →Chemistry · Some Basic Concepts of Chemistry
Consider the following statements regarding the classification of matter: (A) Air is a homogeneous mixture. (B) Glucose contains carbon, hydrogen, and oxygen in a fixed ratio and is classified as a pure substance. (C) The components of a homogeneous mixture are visible distinctly with the unaided eye. (D) Pure substances can have variable composition depending on their preparation method. How many of the above statements are correct?
Read answer →Chemistry · THERMODYNAMICS
2.0 moles of liquid water at \( 100^\circ\text{C} \) is completely converted to ice at \( 0^\circ\text{C} \) at 1 bar pressure. Given that the heat capacity of liquid water is \( 4.2\text{ J g}^{-1\,\circ}\text{C}^{-1} \) and the enthalpy of fusion of ice is \( 6.00\text{ kJ mol}^{-1} \), the total enthalpy change (\( \Delta H \)) for this process is:
Read answer →Chemistry · PYQ NEET UG 2025
For the reaction \( A(g) \rightleftharpoons 2B(g) \), the backward reaction rate constant is higher than the forward reaction rate constant by a factor of 2500, at \( 1000\text{ K} \). [Given : \( R = 0.0831\text{ L atm mol}^{-1}\text{ K}^{-1} \)] \( K_p \) for the reaction at \( 1000\text{ K} \) is
Read answer →Chemistry · Structure of atom
Given below are two statements:\n Statement I: The 4s orbital has a lower \( (n + l) \) value than the 3d orbital, hence 4s fills before 3d.\n Statement II: Valence electrons are those electrons added to the electronic shell with the lowest principal quantum number. \nIn the light of the above statements, choose the most appropriate answer from the options given below:
Read answer →Chemistry · PYQ NEET UG 2019(1)
Which mixture of the solutions will lead to the formation of negatively charged colloidal [\( \text{AgI} \)]\( \text{I}^- \) sol?
Read answer →Chemistry · EQUILIBRIUM
When \( \text{HCl} \) gas is passed through a saturated solution of \( \text{NaCl} \), pure \( \text{NaCl} \) precipitates out while impurities like \( \text{MgSO}_4 \) and \( \text{Na}_2\text{SO}_4 \) remain dissolved. The underlying reason for this phenomenon is:
Read answer →Chemistry · PYQ NEET UG 2022
Match List-I with List-II: List-I (Products formed) List-II (Reaction of carbonyl compound with) i Cyanohydrin a \( \text{NH}_2\text{OH} \) ii Acetal b \( \text{RNH}_2 \) iii Schiff’s base c alcohol iv Oxime d \( \text{HCN} \) Choose the CORRECT answer from the options given below:
Read answer →Chemistry · PYQ NEET UG 2024
Given below are two statements: Statement I : The boiling point of three isomeric pentanes follows the order n-pentane > isopentane > neopentane Statement II : When branching increases, the molecule attains a shape of sphere. This results in smaller surface area for contact, due to which the intermolecular forces between the spherical molecules are weak, thereby lowering the boiling point. In the light of the above statements, choose the most appropriate answer from the options given below:
Read answer →Chemistry · CHEMICAL BONDING AND MOLECULAR STRUCTURE
Consider the following isoelectronic pairs/species: \( \text{N}_2 \), \( \text{CO} \), \( \text{NO}^+ \), \( \text{F}_2 \), and \( \text{O}_2^{2-} \). Let \( S_1 \) be the sum of bond orders of \( \text{N}_2 \), \( \text{CO} \), and \( \text{NO}^+ \), and \( S_2 \) be the sum of bond orders of \( \text{F}_2 \) and \( \text{O}_2^{2-} \). What is the value of \( S_1 - 2S_2 \)?
Read answer →Chemistry · Structure of atom
If the radius of a nucleus of a heavy atom \( A \) is estimated, what is the approximate ratio of the nuclear radius to the radius of its atom if the atomic radius is of the order of \( 10^{-10}\text{ m} \) and nuclear radius is \( 10^{-14}\text{ m} \)?
Read answer →Chemistry · Structure of atom
What is the energy associated with the first orbit in the hydrogen atom given by \( E_1 = -2.18 \times 10^{-18} \text{ J atom}^{-1} \)? What is the energy associated with the fifth orbit?
Read answer →Chemistry · PYQ NEET UG 2017
Predict the CORRECT intermediate and product in the following reaction: \( \text{H}_3\text{C}-\text{C}\equiv\text{CH} \xrightarrow{\text{H}_2\text{O, H}_2\text{SO}_4}{\text{HgSO}_4} \text{ Intermediate (A)} \rightarrow \text{Product (B)} \)
Read answer →Chemistry · Classification of Elements and Periodicity in Properties
Which electronic configuration corresponds to the outermost shell of f-inner transition elements (specifically Lanhanoids and Actinoids)?
Read answer →Chemistry · Some Basic Concepts of Chemistry
What defines a limiting reagent in a chemical reaction?
Read answer →Chemistry · Classification of Elements and Periodicity in Properties
