Tag: water

Questions Related to water

Chloride which is insoluble in water is :

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. sodium chloride

  2. potassium chloride

  3. mercurous chloride

  4. calcium chloride

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Correct Option: C
Explanation:

Chloride salts include sodium chloride (common salt), potassium chloride, calcium chloride, and ammonium chloride. Most chloride salts are readily soluble in water, but mercurous chloride (calomel) and silver chloride are insoluble, and lead chloride is only slightly soluble.

Does $Mg(OH) _2$ react with sodium hydroxide?

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. True

  2. False

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Correct Option: B
Explanation:

A universal indicator is a pH indicator composed of a solution of several compounds that exhibits smooth colour changes over a pH value range from 1-14 to indicate the acidity or alkalinity of solutions. Two basic hydroxides do not react with each other as these are bases but not alkali.

$NaCl + H _2SO _4\overset{\Delta}{\longrightarrow}HCl \ +$

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. $NaHSO _4$

  2. $Na _2SO4$

  3. $Na _2SO _3$

  4. none of the above

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Correct Option: A
Explanation:

Reacting sodium chloride and sulphuric acid at elevated temperature leads to production of sodium bisulphate and hydrogen chloride. Little amount of sodium sulphate is also formed which reacts with the sulphuric acid to yield sodium bisulphate or sodium hydrogen sulphate.
$NaCl\left( s \right) +{ H } _{ 2 }{ SO } _{ 4 }\rightarrow { NaHSO } _{ 4 }\left( s \right) +HCl$

Identify the correct representation of reaction occurring during chloro-alkali process. 

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. $2NaCl(l)+ 2H _2O(l) \rightarrow 2NaOH(l) + Cl _2(g) + H _2(g)$

  2. $2NaCl(s)+ 2H _2O(aq) \rightarrow 2NaOH(aq) + Cl _2(g) + H _2(g)$

  3. $2NaCl(aq)+ 2H _2O(l) \rightarrow 2NaOH(aq) + Cl _2(aq) + H _2(aq)$

  4. $2NaCl(aq)+ 2H _2O(l) \rightarrow 2NaOH(aq) + Cl _2(g) + H _2(g)$

Show answer
Correct Option: D
Explanation:

Chloro-alkali process is an industrial process for the electrolysis of sodium chloride. It is used to produce chlorine and sodium hydroxide. Aqueous sodium chloride or brine ina membrane cell.


At cathode: ${ 2H } _{ 2 }O+2{ e }^{ - }\rightarrow { H } _{ 2 }+{ 2OH }^{ - }$ 

At anode: $2{ Cl }^{ - }\rightarrow { Cl } _{ 2 }+2{ e }^{ - }$ 


$2NaCl(aq)+2{ H } _{ 2 }O\rightarrow { Cl } _{ 2 }(g)+{ H } _{ 2 }(g)+2NaOH(aq)$


Option $(D)$ suggests the correct reaction.

Addition of large quantity of Iron salt will coagulate blood.

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. True

  2. False

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Correct Option: A
Explanation:
Addition of large quantity of Iron salt will coagulate blood. A trivalent iron (ferric ions) generates hydroxyl radicals, which subsequently form soluble plasma fibrinogen (FBG) into an insoluble fibrin clot.

The chemical that changes its colour when it is left open in sunlight is:

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. $FeSO _4\, (s)$

  2. $Pb(NO _3) _2\, (s)$

  3. $AgCl\, (s)$

  4. $BaCl _2\, (aq)$

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Correct Option: C
Explanation:

$AgCl\, (s)$ colors changes when exposed in sunlight.

Which of the following salts when dissolved in water would give acidic solution(s)?

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. $Na _2SO _4$

  2. $(NH _4) _2SO _4$

  3. $CH _3COONa$

  4. $KCI$

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Correct Option: B
Explanation:

Ammonium sulfate reacts with water to form sulfuric acid which is highly acidic in nature as it completely dissociates to give hydrogen ions.

What are the products formed when an aqueous solution of magnesium bicarbonate is boiled?

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. $MgCO _3,\, H _2O,\, CO _2$

  2. $Mg(HCO _3) _2,\, H _2O$

  3. $Mg(OH) _2,\, H _2O$

  4. $Mg,\, CO _2,\, H _2O$

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Correct Option: A
Explanation:

When magnesium bicarbonate is boiled $MgCO _3, H _2O$ and $CO _2$ are formed. A small amount of $Mg(OH) _2$ is also formed.

Reaction: $Mg(HCO _ 3) _2\xrightarrow[\Delta]{} MgCO _ 3+H _ 2O+CO _ 2+Mg(OH) _ 2$

Which of the following salts on heating gives a mixture of two gases?

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. $Ba(NO _3) _2$

  2. $NaNO _3$

  3. $KNO _3$

  4. $RbNO _3$

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Correct Option: A
Explanation:

$(A)$  $Ba(NO _3) _2$


$Reason$ :  The elements in the group 2 includes beryllium($Be$), magnesium($Mg$), calcium($Ca$), strontium($Sr$), barium($Ba$) and radium($Ra$).
The group 2 nitrates, on heating, gives metal oxide, nitrogen dioxide and oxygen gas.
For example - $2Ba(NO _3) _2(s)$ $\rightarrow$ $2BaO(s)$ + $4NO _2(g)$ + $O _2(g)$
Group 2 nitrates also become more thermally stable down the group. 

When hydrated $MgCl _2.\, 6H _2O$ is strongly heated:

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. $MgO$ is formed

  2. $Mg(OH) _2$ is formed

  3. $Mg(OH)Cl$ is formed

  4. Ahydrous $MgCl _2$ is formed

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Correct Option: A
Explanation:

Magnesium hydrochloride is hygroscopic in nature and it loses its water molecules with the formation of magnesium oxide. When mixed with hydrated magnesium oxide, magnesium chloride forms a hard material called Sorel cement.