Q. The change in entropy ( $\Delta S^{o}$ ) will be highest for the which of the following reactions?

NTA AbhyasNTA Abhyas 2020 Report Error

$Ca\left(s\right)+\frac{1}{2}O_{2}\left(g\right) \rightarrow CaO\left(s\right)$

$CaCO_{3}\left(s\right) \rightarrow CaO\left(s\right)+CO_{2}\left(g\right)$

$C\left(g\right)+O_{2}\left(g\right) \rightarrow CO_{2}\left(g\right)$

$N_{2}\left(g\right)+O_{2}\left(\right.g\left.\right) \rightarrow 2NO\left(\right.g\left.\right)$

Solution:

Eq.(b) shows largest phase change $ie$ ,gas $→$ solid

Questions from NTA Abhyas 2020

1. Volume of $0.1 \, \text{M}$ $\text{H}_{2}\text{S}\text{O}_{4}$ required to neutralize $30 \, \text{m}\text{L}$ of $0.2 \, \text{N}$ $\text{N}\text{a}\text{O}\text{H}$ is

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2. The lanthanide contraction is responsible for the fact that

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3. The alkene C₆H₁₀ producing OHC(CH₂)₄CHO on ozonolysis is:

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4. The final step for the extraction of copper from copper pyrite in Bessemer converter involves the reaction-

General Principles and Processes of Isolation of Elements

5. Consider the following diazonium ions :

The order of reactivity towards diazo-coupling with phenol in the presence of dil. NaOH is -

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Chemistry Most Viewed Questions

1. If for a certain reaction $\Delta_{r}H$ is $30\, kJ\, mol^{-1}$ at $450 \,K$, the value of $\Delta_{r}S$ (in $JK^{-1}\, mol^{-1})$ for which the same reaction will be spontaneous at the same temperature is

NEET 2020 Thermodynamics

2. If $8\,g$ of a non-electrolyte solute is dissolved in $114\, g$ of n-octane to reduce its vapour pressure to $80\%$, the molar mass (in $g \,mol^{-1})$ of the solute is [Given that molar mass of n-octane is $114 \,g\, mol^{-1}]$

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3. At standard conditions, if the change in the enthalpy for the following reaction is $-109 \,kJ\, mol^{-1}$ $H_{2(g)}+Br_{2(g)} \to 2HBr_{(g)}$ Given that bond energy of $H_{2}$ and $Br_{2}$ is $435\,KJ\,mol^{-1}$ and $192\,KJ\,mol^{-1}$ , respectively, what is the bond energy (in $KJ \,mol^{-1})$ of $HBr$ ?

NEET 2020 Thermodynamics

4. An organic compound contains $78 \%$ (by wt.) carbon and remaining percentage of hydrogen. The right option for the empirical formula of this compound is: [Atomic wt. of $C$ is $12, H$ is $1$]

NEET 2021 Some Basic Concepts of Chemistry

5. The density of 2 M aqueous solution of NaOH is 1.28 g/cm$^3$. The molality of the solution is
[Given that molecular mass of NaOH = 40 g mol$^{-1}$]

NEET 2019 Some Basic Concepts of Chemistry

6. Given below are half cell reactions:
$ MnO _{4}^{-}+8 H ^{+}+5 e ^{-} \rightarrow Mn ^{2+}+4 H _{2} O $
$ E _{ Mn ^{2+} / MnO _{4}^{-}}^{\circ}=-1.510\, V$
$\frac{1}{2} O _{2}+2 H ^{+}+2 e ^{-} \rightarrow H _{2} O ,$
$ E _{ O _{2} / H _{2} O }^{\circ}=+1.223 \,V$
Will the permanganate ion, $MnO _{4}^{-}$liberate $O _{2}$ from water in the presence of an acid ?

NEET 2022 The d-and f-Block Elements

7. In water saturated air the mole fraction of water vapour is $0.02$. If the total pressure of the saturated air is $1.2\, atm$, the partial pressure of dry air is :

NEET 2019 Solutions

8. Following limiting molar conductivities are given as
$\lambda^{o}_{m}\left(H_{2}SO_{4}\right) \,= \,x S\, cm^{2} mol^{-1}$
$\lambda^{o}_{m}\left(K_{2}SO_{4}\right) = y S\,cm^{2} mol^{-1}$
$\lambda^{o}_{m}\left(CH_{3}COOK\right) =z S\, cm^{2} mol^{-1} $
$\lambda^{o}_{m}\left(in \,S \,cm^{2} mol^{-1}\right)$ for $CH_3COOH$ will be-

NEET 2019 Electrochemistry

9. One atom of an element weighs $ 1.8\times 10^{-22}g$ . Its atomic mass is

Manipal 2009 Some Basic Concepts of Chemistry

10. In the following reaction,
$H_3C-C\equiv CH\xrightarrow [{873\, K}] {\text{red hot iron tube}}$A,
the number of sigma(s) bonds present in the product A is :-

NEET 2019 Hydrocarbons