Tag: bio-chemistry

Questions Related to bio-chemistry

A redox reaction is

bio-chemistry biological oxidation classical idea of redox reactions oxidation reduction redox reaction

  1. exothermic

  2. endothermic

  3. neither exothermic nor endothermic

  4. either exothermic or endothermic

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Correct Option: D

One gas bleaches the colour of flowers by reduction while the other gas by oxidation. The two gases are, respectively:

bio-chemistry biological oxidation classical idea of redox reactions oxidation reduction redox reaction

  1. $CO$ & $Cl _{2}$

  2. $H _{2}S$ & $Br _{2}$

  3. $SO _{2}$ & $Cl _{2}$

  4. $NH _{3}$ & $SO _{3}$

Show answer
Correct Option: C
Explanation:
Sulphur dioxide and chlorine gas are the two gases that bleach the colour of flower by oxidation and reduction.

Chlorine reacts with water and produces a single oxygen atom also called nascent oxygen. This nascent oxygen when combines with any colour make it colourless.

$Cl _{2}+H _{2}O\rightarrow 2HCl+(O)$ (O is oxidizing)

Sulphur dioxide when reacts with coloured substances it releases oxygen from the substance resulting in loss of colour.

$SO _{2}+2H _{2}O\rightarrow H _{2}SO _{4}+2(H)$  (H is reducing)

Hence, the correct option is $C$

What is the oxidation state of P in $Ba(H _2PO _2) _2$?

bio-chemistry biological oxidation classical idea of redox reactions oxidation reduction redox reaction

  1. +1

  2. +2

  3. +3

  4. -1

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Correct Option: A
Explanation:

Oxidation number of $N$ in $HN _3$ ( hydrazoic acid) is:

bio-chemistry biological oxidation classical idea of redox reactions oxidation reduction redox reaction

  1. -1/3

  2. +3

  3. 0

  4. -3

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Correct Option: A

Sulphur dioxide bleaches colouring matter by ___________.

bio-chemistry biological oxidation classical idea of redox reactions oxidation reduction redox reaction

  1. dehydration

  2. oxidation

  3. decomposition

  4. reduction

Show answer
Correct Option: D
Explanation:

Sulphur dioxide bleaches coloring matter by reduction. Bleaching action of sulphur dioxide is not permanent.

$SO _2(g) + 2H _2O \rightarrow H _2SO _4(aq) + 2[H^+]$

When a piece of magnesium ribbon is placed in a beaker of copper sulfate solution, which one of the following is most likely to happen?

bio-chemistry biological oxidation classical idea of redox reactions oxidation reduction redox reaction

  1. A vigorous reaction immediately takes place, with the release of a lot of heat.

  2. The blue colour of the copper sulfate solution gets darker.

  3. The blue colour of the copper sulfate solution gets lighter.

  4. The magnesium catches fire.

Show answer
Correct Option: C
Explanation:

$Mg+CuSO _4 \longrightarrow MgSO _4 + Cu$

            $(Blue)$
By adding$Magnesium$ to $CuSO _4$, it turns to $MgSO _4.$
Because $Mg$ is above $Cu$ in reactivity series. So $Mg$ displaces $Cu$ in $CuSO _4$. As reaction processes, $CuSO _4$ content decreases.
$\therefore$ Color blue fades. 

In the electrochemical series, metals are arranged in order of their tendency to :

bio-chemistry biological oxidation classical idea of redox reactions oxidation reduction redox reaction

  1. release halogens from their salts

  2. become reduced

  3. react with water

  4. lose electrons

Show answer
Correct Option: D
Explanation:

In the electrochemical series, metals are arrange in order of their tendency to lose electrons. 

$\bullet$ Oxidation potential increases down the group.(tendency to lose electron increases).
$\bullet$ Reduction potentials decreases down the group. (tendency to gain $e^-$ decreases).

Which one of the following substances is a good oxidising agent?

bio-chemistry biological oxidation classical idea of redox reactions oxidation reduction redox reaction

  1. coke

  2. water

  3. Hydrogen peroxide

  4. Sulphur dioxide

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Correct Option: C
Explanation:

A good oxidizing agent is one which can readily oxidize other chemical species and reduce itself. Therefore, the compound which is good oxidizing agent must have initial oxidation as high, so that it can reduce its oxidation state and get reduced and oxidize others.

$Coke:$ Reducing agent 
$Hydrogen$ $peroxide$ $(H _2O _2):$ because oxidation state of oxygen is -1 in hydrogen peroxide. So, it oxidizes to 0 & acts as a reducing agent & it reduces to -2 & acts as an oxidizing agent. But, generally, it acts as an oxidizing agent because a stable oxidation state of oxygen is -2(oxide form)
$H _2O:$ Reducing agent.
$SO _2$: sulfur in the +4 oxidation state, sulfur dioxide is a reducing agent. It is oxidized by halogens to give the sulfuryl halides, such as sulfuryl chloride

Hence, the correct option is $\text{C}$

What electrolyte is used to electroplate silver onto a spoon?

bio-chemistry biological oxidation classical idea of redox reactions oxidation reduction redox reaction

  1. pure water

  2. silver nitrate

  3. copper sulfate

  4. acidified water

Show answer
Correct Option: B
Explanation:

$Ans:$ $Silver$ $Nitrate.$

In silver plating, the object (eg.spood) to be plated is made the cathode of an electrolytic cell. The anode is bar of silver metal and the electrodyte must contain $Ag^+$ ions (i.e. $AgNO _3$), so that when the direct current is passed through the cell, positive ($Ag^+$) ions move towards the negative anode (spoon) where they are neutralized by $e^-$ and stick to spoon as silver metal.

Oxalic acid dihydrate, $H _{2}C _{2}O _{4}\cdot 2H _{2}O(s)$ is often used as a primary reagent to standardise sodium hydroxide solution. Which of these facts are reasons to choose this substance as a primary standard?
I. It is diprotic.
II. It is a stable compound that can be weighed directly in air.
III. It is available in pure form.

bio-chemistry biological oxidation classical idea of redox reactions oxidation reduction redox reaction

  1. III only

  2. I and II only

  3. II and III only

  4. I, II and III

Show answer
Correct Option: C
Explanation:

$\begin{array}{l} { H _{ 2 } }{ C _{ 2 } }{ O _{ 4 } }\cdot 2{ H _{ 2 } }O\left( s \right) \to oxadic\, acid\, dihydrate\,  \ Since,\, it\, is\, very\, stable\, and\, also\, available\, in\, pressure \ from\, in\, the\, laboratory\, i.e.\, it's\, always\, used\, as\, primary\, s\tan  dard\, in\, the\, lab. \ Hence,\, the\, option\, C\, is\, the\, correct\, answer. \end{array}$