Tag: chemical reactions

Questions Related to chemical reactions

If equivalent conductance of 1M benzoic acid is $12.8\ { ohm }^{ -1 }{ cm }^{ 2 }$ and if the conductance of benzoate ion and ${ H }^{ -1 }$ ion are 42 and $288.42\ { ohm }^{ -1 }{ cm }^{ 2 }$ respectively. Its degree of dissolution is:

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. 39%

  2. 3.9%

  3. 0.35%

  4. 0.039%

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Correct Option: B
Explanation:

$\Lambda ^{ 0 } _{ m\left( C _{ 6 }H _{ 5 }COOH \right)  }={ \Lambda  } _{ (C _{ 6 }{ H } _{ 5 }CO{ O }^{ - }) }^{ 0 }\quad +{ \Lambda  }^{ 0 } _{ \left( { H }^{ + } \right)  }$ 

$\ \quad \quad \quad \quad \quad \quad \quad \quad =42+288.42=330.42\ now\quad we\quad have,\ \alpha =\frac { { \Lambda  } _{ m }^{ c } }{ { \Lambda  } _{ m }^{ 0 } } =\frac { 12.8 }{ 330.42 } =3.9$

Which of the following decreases on dilution of electrolyte solution?

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. Equivalent conductance

  2. Molar conductance

  3. Specific conductance

  4. Conductance

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Correct Option: B
Explanation:

Conductance $=\cfrac{kA}{l}$ 

where, $k$ is conductivity
$k=K\times G$
where, $K$ is cell constant
Does not depend on volume of the solution but molar conductance.
$\wedge _m=\cfrac{K}{C}$
$C$ is concentration which depends on volume. Hence, affected by dilution.

With rise in temperature, electrolytic conductance :

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. increases

  2. decreases

  3. disappear

  4. none of the above

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Correct Option: A
Explanation:

Generally the conductivity of a solution increases with temperature, as the mobility of the ions increases.
Conductivity (or specific conductance) of an electrolyte solution is a measure of its ability to conduct electricity.
Electrolytic conductance generally increases with rise in temperature.

Conductivity of metal decreases with temperature while conductivity of electrolytic conductors  :

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. increases with temperature

  2. slightly decreases with temperature

  3. remains same

  4. slightly increases with temperature

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Correct Option: A
Explanation:

In metals, conductivity is due to movement of free electrons. When temperature increases, the vibration of metal ions increases. This results in increase in resistance of metal and hence, decrease in conductivity. In electrolytic conductors, the ions are charge carriers and with increase in temperature, ionization increases and hence, conductivity increases.

On increasing temperature, the conduction in metallic conductors :

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. increases

  2. decreases

  3. remains constant

  4. none of the above

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Correct Option: B
Explanation:

Increasing the temperature will inhibit conduction in a metallic conductors because the increased thermal motions of the electrons will tend to interfere with their regular flow in an electric current.

The molar conductivity of cation and anion of salt $BA$ are $180$ and $220\ mhos\ cm^{2} mol^{-2}$ respectively. The molar conductivity of $BA$ at infinite dilution is:

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. $90\ mhos \ cm^{2} mol^{-1}$

  2. $110\ mhos \ cm^{2} mol^{-1}$

  3. $400\ mhos \ cm^{2} mol^{-1}$

  4. $200\ mhos \ cm^{2} mol^{-1}$

Show answer
Correct Option: C

A solution containing one mole per litre of each $Cu(NO _3) _2$, $AgNO _3, Hg _2(NO _3) _2$ and $Mg(NO _3) _2$ is being electrolysed by using inert electrodes. The values of standard electrode potentials in volts(reduction potential) are.
$Ag^+/Ag=+0.80, Hg^{2+} _2/2Hg =+0.79$
$Cu^{2+}/Cu=+0.34, Mg^{2+}/Mg =-2.37$
With increasing voltage, the sequence of deposition of metals on the cathode will be:

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. Ag, Hg, Cu, Mg

  2. Mg, Cu, Hg, Ag

  3. Ag, Hg, Cu

  4. Cu, Hg, Ag

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Correct Option: C

 The standard electrode potentials ${\text{E}} _{{{\text{I}} _2}/{1^ - }}^ \circ ,{\text{E}} _{{\text{B}}{{\text{r}}^ - }/{\text{B}}{{\text{r}} _2}}^ \circ $ and ${\text{E}} _{{\text{Fe/F}}{{\text{e}}^{2 + }}}^ \circ $ are respectively $ + 0.54{\text{V,}} - 1.09{\text{V}}$ and 0.44 V. On the basis of the above data which of the following process is nonspontaneous?

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. ${\text{B}}{{\text{r}} _2} + 2{{\text{I}}^ - }\;{\text{2B}}{{\text{r}}^ - } + {{\text{I}} _2}{\text{ }}$

  2. ${\text{Fe}} + {\text{B}}{{\text{r}} _2}\;{\text{F}}{{\text{e}}^{2 + }} + 2{\text{B}}{{\text{r}}^ - }$

  3. ${\text{Fe}} + {{\text{I}} _2}{\text{ F}}{{\text{e}}^{2 + }} + 2{{\text{I}}^ - }$

  4. ${{\text{I}} _2} + 2{\text{B}}{{\text{r}}^ - }2{{\text{I}}^ - } + {\text{B}}{{\text{r}} _2}$

Show answer
Correct Option: D
Explanation:

the one which is having higher oxidation potential will undergo oxidation,

in D, $I^-$ is having lower reduction potential in comparison to $Br^-$, so has to undergo oxidation but in option D, it is getting oxidized.
hence, it is a nonspontaneous reaction.

An alkali which dissociates partially on passage of an electric current is:

metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

  1. sodium hydroxide

  2. nickel metal

  3. ammonium hydroxide

  4. copper

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Correct Option: C
Explanation:

We have,

Sodium chloride is an ionic compound which is already present in the ionic form and completely dissociated on the passage of electric current,
Nickel and copper metal have higher reduction potential so, reduction takes place on passage of electric current,
ammonium hydroxide is a weak base it is partially dissociated on the passage of electric current. 

Which of the following is/are true regarding rancidity?

chemistry chemical reactions effects of oxidation reactions in daily life corrosion of metals electroplating and its application

  1. On keeping for long time, the oxidation of oils and fats, changes the taste and odour of food.

  2. To prevent rancidity, food is stored in air tight containers.

  3. Rancidity can also be prevented by addition of antioxidants.

  4. To prevent rancidity, packed food items are flushed with an inert gas like nitrogen.

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

The following are true regarding rancidity. On keeping for long time, the oxidation of oils and fats, changes the taste and odor of food and makes them unfit for consumption. To prevent rancidity, food is stored in air tight containers. Rancidity can also be prevented by addition of antioxidants. To prevent rancidity, packed food items are flushed with an inert gas like nitrogen.