Tag: substances in common use

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Questions Related to substances in common use

Multiple choice chemistry substances in common use common salt some useful compounds in everyday life salts and their properties study of some important salts salts used in daily life

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
Reveal answer Fill a bubble to check yourself
D Correct answer
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).

Multiple choice chemistry substances in common use common salt some useful compounds in everyday life salts and their properties study of some important salts salts used in daily life

Bleaching powder is made up of : 

  1. lime and chlorine

  2. soda ash and chlorine

  3. chlorine and charcoal

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Calcium hydroxide on reaction with chlorine produces bleaching powder. 


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

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

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. $Na+Cl _{2}+O _{2}$
Reveal answer Fill a bubble to check yourself
C Correct answer
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.
Multiple choice chemistry substances in common use salts and their properties study of some important salts salts used in daily life

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

  1. $NaHCO _3$
  2. $MgCO _3$
  3. $MgCl _2$
  4. $NaI$
Reveal answer Fill a bubble to check yourself
C Correct answer
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% 
Multiple choice chemistry substances in common use salts and their properties study of some important salts salts used in daily life

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

  1. $Ca$
  2. $Al$
  3. $Na$
  4. $Fe$
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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
Reveal answer Fill a bubble to check yourself
C Correct answer
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.
Multiple choice chemistry substances in common use salts and their properties study of some important salts salts used in daily life

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
Reveal answer Fill a bubble to check yourself
B Correct answer
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.