Tag: chemistry

Questions Related to chemistry

In a Daniell cell:

chemistry oxidation- reduction reactions redox reactions and electrode processes redox and electrode processes applications of redox reaction

  1. The chemical energy liberated during the redox reaction is converted to electrical energy

  2. The electrical energy of the cell is converted to chemical energy

  3. The energy of the cell is utilised in conduction of the redox reaction

  4. The potential energy of the cell is converted into electrical energy

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Correct Option: A
Explanation:

A galvanic cell is an electrochemical cell that derives electrical energy from spontaneous redox reactions taking place within the cell. It generally consists of two different metals connected by a salt bridge, or individual half-cells separated by a porous membrane. Daniel cell is a galvanic cell.

Daniel cell has Zn as anode and Cu as cathode. The reactions of Daniel cell are,

At anode(Oxidation),

$Zn(s)\rightarrow Zn^{2+}(aq)+2e^{-}$

At cathode(Reduction),

$Cu^{2+}(aq)+2e^{-}\rightarrow Cu(s)$

Hence overall reaction is,

$Zn(s)+Cu^{2+}(aq)\rightarrow Zn^{2+}(aq)+Cu(s)$

Here the chemical energy is liberated when the redox reaction takes place in the cell and it is converted into electrical energy.

Which one is not correct for e.m.f. of a galvanic cell?

chemistry oxidation- reduction reactions redox reactions and electrode processes redox and electrode processes applications of redox reaction

  1. $E _{cell} = E _{OP _{anode}} + E _{RP _{cathode}}$

  2. $E _{cell} = E _{OP _{LHS}} + E _{RP _{RHS}}$

  3. $E _{cell} =$ higher oxidation potential - lower oxidation potential

  4. $E _{cell} =$ lower oxidation potential - higher oxidation potential

Show answer
Correct Option: A,B,C
Explanation:

The correct expressions for the standard cell potentials of a galvanic cell are as given below.
$E _{cell} = E _{OP _{anode}} + E _{OP _{cathode}}$
$E _{cell} = E _{OP _{LHS}} + E _{OP _{RHS}}$
$E _{cell} =$lower oxidation potential $-$ higher oxidation potential.
Thus, only option D is correct and options A to C are incorrect.

Identify the true statement regarding Daniel cell:

chemistry oxidation- reduction reactions redox reactions and electrode processes redox and electrode processes applications of redox reaction

  1. Zinc ions flows across salt bridge 

  2. ${K}^{+}$ ions move from salt bridge to $Cu/{Cu}^{+2}$ half cell

  3. Oxidation takes place at copper electrode

  4. Flow of current takes place from copper electrode to zinc electrode

Show answer
Correct Option: D
Explanation:

Daniell cell is  perform the spontaneous redox reaction between zinc and cupric ions to produce an electric current. It consists of two half-cells. The  left half cell contains a zinc metal electrode dipped in $ZnSO _4$ solution.The half right half cell consists of copper metal electrode in a solution $CuSO _4$. The half-cells are joined by a salt bridge that prevents the mixing of the solution.
In Daniel cell flow of current takes place from copper electrode to zinc electrode.
Hence option D is correct.

For the galvanic cell, $Cu|Cu^{2+}||Ag^+|Ag$. Which of the following observations is not correct?

chemistry oxidation- reduction reactions redox reactions and electrode processes redox and electrode processes applications of redox reaction

  1. Cu acts as anode and Ag acts as cathode

  2. Ag electrode loses mass and Cu electrode gains mass

  3. Reaction at anode, $Cu\rightarrow Cu^{2+}+2e^-$

  4. Copper is more reactive than silver

Show answer
Correct Option: B
Explanation:

Redox reactions are reactions in which both oxidation and reduction takes place together. In a Galvanic cell oxidation occurs at anode and reduction occurs at cathode. Here $Cu$ is an anode and $Ag$ is a cathode. As in Oxidation, the electrons get released to form aqueous ions in the solution and hence reduces the mass of the electrode as the electrons are released from the electrode. Here,$Cu$ electrode loses mass. Similarly,the released electrons are gained by silver ions i.e $Ag^ { +} $ and the electrode mass of $Ag$ gets increased. Hence, B is the wrong option.

On the Mulliken scale, the average of ionization potential and electrons affinity is known as _____(electronegativity/affinity).

chemistry classification of elements- the periodic table periodic trends in physical properties properties and trend trends in periodic table electronic configuration and valency electron configuration

  1. electronegativity

  2. electroneaffinity

  3. electropositivity

  4. none

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Correct Option: A
Explanation:

On Mulliken scale, the average of ionization potential and electrons affinity is known as electronegativity.

If the E.N. value of Nitrogen in the pauling scale is 3.0, then he value in mulliken scale will be

chemistry classification of elements- the periodic table periodic trends in physical properties properties and trend trends in periodic table electronic configuration and valency electron configuration

  1. $11.2$

  2. $22.4$

  3. $8.4$

  4. $3.0$

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Correct Option: C

Which of the following is the correct order of hydrated radii?

chemistry classification of elements- the periodic table periodic trends in physical properties properties and trend trends in periodic table electronic configuration and valency electron configuration

  1. $Li^{+} < Na^{+} < K^{+} < Rb^{+} < Cs^{+}$

  2. $Rb^{+} < Na^{+} < Li ^{+} < Cs^{+} < K^{+}$

  3. $Cs^{+} < Rb^{+} < K^{+} < Na ^{+}< Li^{+}$

  4. $Li^{+} < K^{+} < Na^{+} < Rb ^{+} < Cs ^{+}$

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Correct Option: A

Electronegativity of $F$ on Pauling's scale is 4.0. The value on Mulliken's scale is:

chemistry classification of elements- the periodic table periodic trends in physical properties properties and trend trends in periodic table electronic configuration and valency electron configuration

  1. $11.2$

  2. $14.4$

  3. $16.8$

  4. None of these

Show answer
Correct Option: A
Explanation:

Mulliken proposed that the arithmetic mean of the first ionization energy (I) and the electron affinity (Eea) should be a measure of the tendency of an atom to attract electrons.
$X= \dfrac{E _i + E _{Ea}}{2}$
Electronegativity of $F$ on Mulliken's scale is hence $11.2$

EN(mulliken scale) of the element (A) is $E _1$ and IP is $E _2$. Hence, EA will be:

chemistry classification of elements- the periodic table periodic trends in physical properties properties and trend trends in periodic table electronic configuration and valency electron configuration

  1. $2E _1 - E _2$

  2. $E _1 - E _2$

  3. $E _1 - 2E _2$

  4. $(E _1 + E _2)/2$

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Correct Option: A
Explanation:

As we know,
$\displaystyle EN = \frac{(IP) + (EA)}{2}$ 


$EA = 2 EN - IP$

$EA = 2E _1 - E _2$

The ionic radii of ${Rb}^{+}$ and ${I}^{-}$ are $1.46$ and $2.16$ $\mathring { A } $, respectively. The most probable type of structure exhibited by it is

chemistry classification of elements- the periodic table periodic trends in physical properties properties and trend trends in periodic table electronic configuration and valency electron configuration

  1. $CsCl$ type

  2. $NaCl$ type

  3. $ZnS$ type

  4. $Ca{F} _{2}$ type

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Correct Option: B