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Salts used in daily life - class-X

Description: salts used in daily life
Number of Questions: 21
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Tags: s-block elements the s-block elements (alkali and alkaline earth metals) acids, bases and salts the s-block elements chemistry substances in common use
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The uses of bleaching powder are:

  1. it is used for bleaching cotton

  2. it is used as an oxidizing agent in chemical industries

  3. it can be used for disinfecting water

  4. all of the above


Correct Option: D
Explanation:

Bleaching powder $(CaOCl _2)$ has many uses and some of them are as follows :-

1.It is used in bleaching dirty clothes in launder, as a bleaching agent in cotton and linen in the textile industry.
2.Due to evolution of nascent oxygen, it is used as an oxidizing agent in the chemical industries.
3.It can be used as a disinfectant which can be used for disinfecting water to make it potable.
Hence, the correct answer is option (D).

Bleaching powder is made up of : 

  1. lime and chlorine

  2. soda ash and chlorine

  3. chlorine and charcoal

  4. none of these


Correct Option: A
Explanation:

Calcium hydroxide on reaction with chlorine produces bleaching powder. 


$Ca(OH) _2+Cl _2\to Ca(OCl)Cl+H _2O$                     

Common salt is chemically sodium chloride ($NaCl$).

  1. True

  2. False


Correct Option: A
Explanation:

The well-known table salt is chemically sodium chloride. Its chemical formula is $NaCl$.

The product of electrolysis of conc. solution of common salt is?

  1. $Na+Cl _{2}$

  2. $H _{2}+O _{2}$

  3. $NaOH+H _{2}+Cl _{2}$

  4. $Na+Cl _{2}+O _{2}$


Correct Option: C
Explanation:

The ionization of salt:

$NaCl\rightarrow Na^{+}+Cl^{-}$

The half-reaction at the cathode is:

$H _2O+2e^{−}\rightarrow H _2+2OH^{−}$

Here, the reduction is taking place.

The half-reaction at the anode is:

$2Cl^{-}\rightarrow Cl _2+1e^{−}$

Here, oxidation is taking place.

The overall reaction is as follows:

$NaCl+H _2O\rightarrow Na^{+}+OH^{−}+H _2+Cl _2$.

Hence, option $C$ is correct.

Which of the following is not hydroscopic-

  1. NaCl

  2. ${\text{MgC}}{{\text{l}} _{2\;\;}}$

  3. ${\text{CaC}}{{\text{l}} _{2\;\;}}$

  4. LiCl


Correct Option: D

Molten NaCl conducts electricity due to the presence of :

  1. free molecules

  2. free ions

  3. free electrons

  4. free atoms


Correct Option: B
Explanation:

As NaCl is ionic compound so in molten states it will form $Na^+$ and $Cl^-$ ion and these ions conduct electricity.

Which impurity (as a salt) is associated with table salt obtained from sea-water?

  1. $NaHCO _3$

  2. $MgCO _3$

  3. $MgCl _2$

  4. $NaI$


Correct Option: C
Explanation:

Sea water contains $MgCl _2$ brine so salt made from sea water contains this as impurity.
sea salt:

 Chloride $(Cl^-)$  55.03%
 Sodium $(Na^+)$  30.59%
 Sulfate $(SO _4^{2-}$ 7.68% 
 Magnesium $(Mg^{2+})$ 3.68% 
 Calcium $(Ca^{2+})$ 1.18% 
 Potassium $(K^+)$ 1.11% 
 Bicarbonate $(HCO _3^-)$ 0.41% 
 Bromide $(Br^-)$ 0.19% 

The metal whose hydroxide does not decompose on heating but its nitrate decomposes is:

  1. $Ca$

  2. $Al$

  3. $Na$

  4. $Fe$


Correct Option: C
Explanation:

$NaOH \xrightarrow {heat} $ no reaction
$NaNO _3 \xrightarrow {heat} NaNO _2+\frac{1}{2}O _2$

The metal whose hydroxide does not decompose on heating but its nitrate decomposes is sodium.

Sodium chloride imparts a yellow color to the Bunsen flame. This can be interpreted due to the :

  1. low ionisation of energy of sodium

  2. sublimation of metalic sodium to give yellow vapour

  3. emission of excess energy absorbed as a radiation in the visible region

  4. photo sensitivity of sodium


Correct Option: C
Explanation:
Sodium chloride imparts a yellow color to the Bunsen flame. This can be interpreted due to the emission of excess energy absorbed as a radiation in the visible region.
When an alkali or akaline earth metal (or its salt) is introduced in the flame, the valence electrons of the metal absorbs energy and are excited to the higher energy level. When excited electrons return to their ground state, they release the absorbed energy as visible light.

Commercial common salts become slightly damp on keeping. This is due to the fact that:

  1. common salt is hygroscopic

  2. common salt contains some impurities which are hygroscopic

  3. common salt is efflorescent

  4. common salt is crystalline


Correct Option: B
Explanation:

Commercial common salt commonly becomes slightly damp on keeping because common salt contains some impurities like ${MgCl _2}$ and ${CaCl _2}$ which are hygroscopic in nature and absorb moisture from the atmosphere.
Hence, option B is correct.

Which one of the following products is formed when a mixture of steam, sulphur dioxide gas and oxygen gas (from air) is passed over dry lumps of common salt, the sodium chloride?

  1. $ Na _2SO _3 $

  2. $ Cl _3 $

  3. $ NaHSO _3 $

  4. $ Na _2SO _4 $


Correct Option: D
Explanation:

Hargreaves process:
$ 4NaCl (s) + 2SO _2 (g) + 2H _2O (g) + O _2 (g) \longrightarrow 2Na _2SO _4 + 4HCl $

Reaction, $Cl _2 + 2NaOH \rightarrow P$            

What are the products?

  1. $NaCl + NaOCl + H _2$

  2. $NaCl + NaOCl + H _2O _2$

  3. $NaCl + NaOCl + H _2O$

  4. $NaCl + NaOCl + O _2$


Correct Option: C
Explanation:

The reaction of non-metals with bases is complex. Example: When chlorine reacts with a base like sodium hydroxide, it gives multiple products like sodium hypochlorite, sodium chloride and water.

$Cl _2 + 2NaOH \rightarrow NaCl + NaOCl + H _2O$

The commercial salt is purified by passing :

  1. $H _2S$ gas through an alkaline solution ofsalt

  2. HCI gas through a saturated solution of salt

  3. $H _2$ gas through a solution of salt

  4. $CI _2$ gas through a saturated solution of salt


Correct Option: B
Explanation:

The common table salt is prepared by passing HCI gas through a saturated solution of salt. The precipitation is due to common ion effect.

$\underset { Salt\,solution }{ NaCl }+H^++Cl^-\longrightarrow  \underset { ppt}{ NaCl } $

Hence, option B is correct.

Statement 1: One mole of NaCl contains $2$ moles of ions.
Statement 2: NaCl is a stable salt at room temperature.

  1. Both Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1.

  2. Both Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation of Statement 1.

  3. Statement 1 is correct but Statement 2 is not correct.

  4. Statement 1 is not correct but Statement 2 is  correct.

  5. Both the Statement 1 and Statement 2 are not correct


Correct Option: B
Explanation:

Option (B) is correct.

Statement 1:  One mole of $NaCl$ contains 2 moles of ions i.e. a mole of chloride and a mole of sodium.Every $NaCl$ molecules has a $Na$ and a $Cl^-$ atom. So, if you have $6.022x10^{23}$ molecules, you will have that same number of $Na$ atoms and $Cl^-$ atoms, and by definition, 1 mole is $6.022x10^{23} $atoms.

Statement 2: $NaCl$ is a stable salt at room temperature.Sodium and chlorine forms a strong ionic bond, completing the octet of both atoms.They are arranged in a face centered cubic crystal structure where each $Na^+$ or $Cl^-$ ion is surrounded by 6 of the opposite ions forming an octahedron. This makes sodium chloride a stable compound.

Statement 1: Crystals of sodium chloride go into aqueous solution as ions.
Statement 2: The sodium ion has a $1+$ change and the chloride ion has a $1-$ charge and they are hydrated by the water molecules.

  1. Both Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1.

  2. Both Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation of Statement 1.

  3. Statement 1 is correct but Statement 2 is not correct.

  4. Statement 1 is not correct but Statement 2 is correct.

  5. Both the Statement 1 and Statement 2 are not correct.


Correct Option: A
Explanation:

Statement 1: Crystals of sodium chloride go into aqueous solution as ions.
$\displaystyle NaCl \rightleftharpoons Na^+ (aq) + Cl^- (aq) $
Statement 2: The sodium ion has a $1+$ change and the chloride ion has a $1−$ charge and they are hydrated by the water molecules.
Each sodium ion ( or each chloride ion) is surrounded by several water molecules.
Both Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1.

The type of bonding present in a substance can be determined from experimental data.
Based on the information in the table below, which of the following substances is most likely to represent the identity of the solid?

Melting Point Density Conductivity Alone Conductivity in Aqueous Solution
$801^{\circ}C$ $2.17\ g/cc$ None Excellent
  1. Platinum, $Pt$

  2. Sodium chloride, $NaCl$

  3. Glucose, $C _{6}H _{12}O _{6}$

  4. Quartz, $SiO _{2}$


Correct Option: B

Which of the following materials conducts electricity?

  1. Crystalline potassium chloride

  2. Fused sulphur

  3. Molten sodium chloride

  4. Diamond


Correct Option: C
Explanation:

In crystalline solids, the ions are tightly bound by strong coulombic force of attraction having greater interatomic interaction and less interparticle space. $ { Na }^{ + }$ and ${ Cl }^{ - } $ ions are free to move only in molten state or aqueous solution. Hence, they show electrical conductivity in molten state.

Brine is:

  1. aqueous solution of chloride

  2. saturated solution of $NaCl$

  3. aqueous solution of $HCl$

  4. common name of bleaching powder


Correct Option: B
Explanation:

Brine is a solution of salt ( usually sodium chloride ) in water.

Molten $NaCl$ conducts electricity due to the presence of:

  1. Free molecules

  2. Free ions

  3. Free electrons

  4. Free atoms


Correct Option: B
Explanation:

Molten sodium chloride contains sodium ions and chloride ions which are free to move. 


Hence molten sodium chloride conducts electricity.

Option B is correct.

Crude common salt is hygroscopic because of impurities of:

  1. $CaSO _{4}$ and $MgSO _{4}$

  2. $CaCl _{2}$ and $MgCl _{2}$

  3. $CaBr _{2}$ and $MgBr _{2}$

  4. $Ca\left ( HCO _{3} \right ) _{2}$ and $Mg\left ( HCO _{3} \right ) _{2}$


Correct Option: B
Explanation:

Crude common salt contains impurities such as $ CaSO _{ 4 },   CaCl _{ 2 } ,   MgCl _{ 2} $. Hence it is deliquescent (hygroscopic).

Hence option B is correct.

Molten sodium chloride conducts electric current due to the presence of:

  1. free electrons

  2. free mobile ions

  3. immobile ions

  4. none of these


Correct Option: B
Explanation:

Current is the rate of flow of charge. NaCl is an ionic solid. An ionic solid consists of a lattice of ${ Na }^{ + }$ and ${ Cl }^{ - }$ ions in which these ions are fixed in their places. Solid NaCl does not contain any mobile charge carriers that can facilitate the flow of charge. But molten NaCl contains free mobile ions ${ Na }^{ + }$ and ${ Cl }^{ - }$ ions which allow the passage of current.


Thus, molten NaCl conducts electric current due to the presence of free mobile ions.

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