Tag: chemistry

Questions Related to chemistry

The passage of electricity in the Daniell cell when $Zn$ and $Cu$ electrodes are connected is from:

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

  1. $Cu$ to $Zn$ in the cell

  2. $Cu$ to $Zn$ outside the cell

  3. $Zn$ to $Cu$ outside the cell

  4. $Zn$ to $Cu$ in the cell

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Correct Option: B
Explanation:

In Daniell cell, Zn acts an anode and Cu acts as cathode, electron flow takes place from anode to cathode and hence, electricity flows from Cu to Zn outside the cell.

Daniel cell operates under nonstandard state conditions. If the equation of the cell reaction is multiplied by 2 then:

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

  1. $E$ and $E^o$ remain unchanged

  2. $E$ is doubled

  3. $n$ remains unchanged in Nernst equation

  4. $Q$ is halved in Nernst equation

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Correct Option: A
Explanation:

Nernst's equation states ${ E } _{ cell }={ E } _{ cell }^{ 0 }+\dfrac { RT }{ nF } ln\left[ { M }^{ + } \right] $

Where $E$ and ${ E }^{ 0 }$ of cell are independent of volume/quantity of reacting species in electrolyte, they are intunsic properties of cell. Hence, on doubling cell equation of Daniel cell.
$Zn\left| { Zn }^{ 2+ } \right| \left| { Cu }^{ 2+ } \right| Cu$,
its e.m.f $(E)$ and standard e.m.f $\left( { E }^{ 0 } \right) $ remain unchanged where ${ E }^{ 0 }$ stays at $1.09V$.

For the Daniel cell involving the cell reaction${ Zn } _{ (s) }+{ { Cu }^{ +2 } } _{ (aq) }\rightleftharpoons { { { Zn }^{ +2 } } } _{ (aq) }+{ Cu } _{ (s) }$ the standard free energies of formation of  ${ Zn } _{ (s) }$, ${ Cu } _{ (s) }$, ${ { Cu }^{ +2 } } _{ (aq) }$ and ${ { { Zn }^{ +2 } } } _{ (aq) }$ are 0, 0, 64.4 KJ/Mole and -154.0 KJ/Mole, respectively. Calculate the standard EMF of the cell?

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

  1. $2.13 Volts$

  2. $1.13 Volts$

  3. $2.26 Volts$

  4. $3.42 Volts$

Show answer
Correct Option: B
Explanation:

$\because \quad \Delta { G }^{ 0 }=\left( { G } _{ { Zn }^{ 2+ } }^{ 0 }-{ G } _{ { Cu }^{ 2+ } }^{ 0 } \right) $ $= (-154-64.4) KJ/Mole$

$\therefore(-2\times{E}^{0}\times F)$ $=(-218.4\times {10}^3)$
$\therefore E^0=1.1316\quad volt$

Which of the following statement is TRUE for the electrochemical Daniel cell :

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

  1. Electron flow from Zinc electrode to Copper electrode.

  2. Current flows from zinc electrode to copper electrode.

  3. Cation moves towards copper electrode.

  4. Cation moves towards zinc electrode.

Show answer
Correct Option: A
Explanation:

During reaction of $Zn\rightarrow{Zn}^{2+}+{2e}^{-}$ extra electron goes from anode to cathode or flow of $e^-$ from Zinc to Copper takes place and current flows from Copper to Zinc.

Nucleic acids are the polymers of __________

biochemical polymers polymerisation chemistry

  1. nucleosides

  2. nucleotides

  3. bases

  4. sugars

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Correct Option: B
Explanation:

Nucleic acids are made up of individual monomers called nucleotides

Which of the following is correxect bonding in nucleotide?

biochemical polymers polymerisation chemistry

  1. $A - T, \ G - C$

  2. $A - G,\ T - C$

  3. $G - T,\ A - C$

  4. $A - A,\ T - T$

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Correct Option: A
Explanation:

The correct bonding pairs in Nucleotide are Adenine- Thymine, Guanine- Cytosine where Adenine, Thymine, Guanine, Cytosine are bases which form in pairs to build up Nucleotides.

A unit in nucleic acid which contains 'base-sugar phosphate' unit is called ?

biochemical polymers polymerisation chemistry

  1. nuleotide

  2. nucleoside

  3. phosphotide

  4. polypeptide

Show answer
Correct Option: A
Explanation:
Nucleotides are composed of three sub-unit molecules: a nitrogenous base, a five-carbon sugar (ribose or deoxyribose), and at least one phosphate group.

Which of the following bases is not present in DNA?

biochemical polymers polymerisation chemistry

  1. Adenine

  2. Thymine

  3. Cytosine

  4. Uracil

Show answer
Correct Option: D
Explanation:
In DNA, four bases have been found. They are adenine (A), guanine (G), cytosine (C) and thymine (T).
Uracil is present in RNA.

The $AT/GC$ ratio in human beings is: (where $A=$adenine,$T=$thymine,$G=$Guanine,$C=$cytosine)

biochemical polymers polymerisation chemistry

  1. $1$

  2. $1.52$

  3. $9.3$

  4. $2$

Show answer
Correct Option: B
Explanation:

A-T/G-C ratio is human beings is equal to 1.52

where A=Adenine T-Thymine, G-Guanine, C-Cytosine

RNA is ?

biochemical polymers polymerisation chemistry

  1. single helix strand

  2. double helix strand

  3. right hand twisted double helix strand

  4. triple helix strand

Show answer
Correct Option: A
Explanation:
RNA is a single-stranded molecule in many of its biological roles and consists of a much shorter chain of nucleotides.