Tag: salts and their properties

Questions Related to salts and their properties

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

chemistry substances in common use salts and their properties study of some important salts salts used in daily life

  1. True

  2. False

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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?

chemistry substances in common use salts and their properties study of some important salts salts used in daily life

  1. $Na+Cl _{2}$

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

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

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

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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-

chemistry substances in common use salts and their properties study of some important salts salts used in daily life

  1. NaCl

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

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

  4. LiCl

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Correct Option: D

Molten NaCl conducts electricity due to the presence of :

chemistry substances in common use salts and their properties study of some important salts salts used in daily life

  1. free molecules

  2. free ions

  3. free electrons

  4. free atoms

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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?

chemistry substances in common use salts and their properties study of some important salts salts used in daily life

  1. $NaHCO _3$

  2. $MgCO _3$

  3. $MgCl _2$

  4. $NaI$

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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:

chemistry substances in common use salts and their properties study of some important salts salts used in daily life

  1. $Ca$

  2. $Al$

  3. $Na$

  4. $Fe$

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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 :

chemistry substances in common use salts and their properties study of some important salts salts used in daily life

  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

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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:

chemistry substances in common use salts and their properties study of some important salts salts used in daily life

  1. common salt is hygroscopic

  2. common salt contains some impurities which are hygroscopic

  3. common salt is efflorescent

  4. common salt is crystalline

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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?

chemistry substances in common use salts and their properties study of some important salts salts used in daily life

  1. $ Na _2SO _3 $

  2. $ Cl _3 $

  3. $ NaHSO _3 $

  4. $ Na _2SO _4 $

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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?

chemistry substances in common use salts and their properties study of some important salts salts used in daily life

  1. $NaCl + NaOCl + H _2$

  2. $NaCl + NaOCl + H _2O _2$

  3. $NaCl + NaOCl + H _2O$

  4. $NaCl + NaOCl + O _2$

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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.

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