Tag: chemistry

Questions Related to chemistry

Bleaching powder has several uses, some of which are mentioned here. Pick the false one.

chemistry substances in common use chemical from common salt compounds of carbon some useful compounds in everyday life

  1. For decolourising sugar

  2. For bleaching paper pulp

  3. For sterilizing water

  4. For making chloroform

Show answer
Correct Option: A
Explanation:

Bleaching powder is used for bleaching dirty clothes in the laundry, as a bleaching agent for cotton and linen in the textile industry. It is a strong oxidizing agent hence used as an oxidizer in many industries. It is used as a disinfectant which is used for disinfecting water to make potable water.It is also used for bleaching paper pulp,sterilizing water,making chloroform.

It is not used to decolourize sugar and hence option A is false one.

Which of the following can act as a catalyst in the decomposition of bleaching powder?

chemistry substances in common use chemical from common salt compounds of carbon some useful compounds in everyday life

  1. Cobalt chloride

  2. Cobalt

  3. Chlorine

  4. None of the above

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Correct Option: A,B
Explanation:

Heavy metals like Ni, Co, Mn, Cu and their chlorides accelerate the decomposition of bleaching powder.

When bleaching powder undergoes auto-oxidation, the change in oxidation state is:

chemistry substances in common use chemical from common salt compounds of carbon some useful compounds in everyday life

  1. $+1 \ to +5$

  2. $-1\  to\  0$

  3. $+1 \ to +3$

  4. $-1\  to +3$

Show answer
Correct Option: A
Explanation:

$6Ca(OCl) _2 \rightarrow 6Ca(ClO _3) _2 + 5CaCl _2$

On treating bleaching powder with ethyl alcohol it gives chloroform.

chemistry substances in common use chemical from common salt compounds of carbon some useful compounds in everyday life

  1. True

  2. False

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Correct Option: A
Explanation:

${ CaOCl } _{ 2 }+{ C } _{ 2 }{ H } _{ 5 }OH\rightarrow { CHCl } _{ 3 }+Ca{ \left( OH \right)  } _{ 2 }$

Bleaching powder is obtained by the reaction of $Cl _{2}$ with:

chemistry substances in common use chemical from common salt compounds of carbon some useful compounds in everyday life

  1. dilute solution of $Ca[OH] _{2}$

  2. concentrated solution of $Ca[OH] _{2}$

  3. dry $CaO$

  4. dry slaked lime

Show answer
Correct Option: B
Explanation:

$2Cl _2 + 2Ca(OH) _2(conc.) \rightarrow Ca(OCl) _2 + CaCl _2 + 2H _2O$

State whether the given statement is true or false:

Bleaching powder contains about 50 % available chlorine.

chemistry substances in common use chemical from common salt compounds of carbon some useful compounds in everyday life

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

Calcium hypochlorite is a relatively stable compound and has a greater available chlorine than sodium hypochlorite. It strongly smells of chlorine owing to its slow decomposition in moist air.The percentage of chlorine in bleaching powder is between range 10 % to 40%.

Hence,it is false.

Available chlorine can be liberated from bleaching powder by the reaction with:

chemistry substances in common use chemical from common salt compounds of carbon some useful compounds in everyday life

  1. $conc.H _{2}SO _{4}$

  2. $dil. H _{2}SO _{4}$

  3. $CO _{2}$

  4. $dil. HNO _{3}$

Show answer
Correct Option: B,C,D
Explanation:

Available chlorine in bleaching powder is the amount of chlorine liberated by the action of dilute acids on bleaching powder.

On long standing, bleaching powder undergoes auto oxidation.

chemistry substances in common use chemical from common salt compounds of carbon some useful compounds in everyday life

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

On long standing, bleaching powder undergoes auto-oxidation which results in the formation of calcium chloride and calcium chlorate.


$6 CaOCl _2 \rightarrow5CaCl _2   + 6 Ca(ClO3) _2 $

Hence, the given statement is $true$

Substance $X$:
(I) reacts with $H _2S$ to produce white turbidity.
(II) changes light green solution of $FeSO _4$ into yellow colour.
(III) reacts with moisture to give pungent smelling gas.
Hence $X$ is:

chemistry substances in common use chemical from common salt compounds of carbon some useful compounds in everyday life

  1. $KMnO _4$

  2. $K _2Cr _2O _7$

  3. $SO _2$

  4. $CaOCl _2$

Show answer
Correct Option: D
Explanation:

$CaOCl _2+H _2O\rightarrow Ca(OH) _2+\underset {(\text {Pungent smelling gas})}{Cl _2}\uparrow$
$H _2S+Cl _2\rightarrow 2HCl+\underset {(\text {White turbidity})}{S}$
$\underset {(\text {Light green})}{2FeSO _4}+H _2SO _4+Cl _2\rightarrow Fe _2(SO _4) _3+2HCl$

The bleaching property of chlorine water is due to:

chemistry substances in common use chemical from common salt compounds of carbon some useful compounds in everyday life

  1. formation of nascent oxygen

  2. formation of nascent chlorine

  3. formation of ${O} _{3}$

  4. reducing property of ${Cl} _{2}$

Show answer
Correct Option: A
Explanation:
${ Cl } _{ 2 }+{ H } _{ 2 }O\rightarrow HCl+HOCl\rightarrow 2HCl+\left[ 0 \right] $
$\left[ 0 \right] $-Nascent oxygen
Chlorine water act as strong oxidizing agent because of nascent oxygen produced in water.