Tag: chemistry

Questions Related to chemistry

What is used as a bleaching linen, wood pulp and washed clothes in laundry?

  1. Baking soda

  2. Washing soda

  3. Bleaching powder

  4. Plaster of paris


Correct Option: C
Explanation:

Bleaching powder is used as bleaching linen, wood pulp and washed clothes in laundry.

Calcium hydroxide react with chlorine to form:

  1. bicarbonate

  2. bleaching powder

  3. baking soda

  4. washing soda


Correct Option: B
Explanation:

Calcium hypochlorite is an inorganic compound with formula $Ca(ClO) _2$. Calcium hydroxide and chlorine form bleaching powder. 

Formula of calcium hypochlorite is:

  1. $CO{ Cl } _{ 2 }$

  2. $Ca{ \left( ClO \right) } _{ 2 }$

  3. $Ca{ \left( Cl{ O } _{ 3 } \right) } _{ 2 }$

  4. $Ca{ \left( Cl{ O } _{ 4 } \right) } _{ 2 }$


Correct Option: B
Explanation:

Formula of $calcium : hypochlorite$ is $\displaystyle Ca(ClO) _2$
$\displaystyle CaOCl _2$ represents $\displaystyle calcium : chlorohypochlorite$. It is known as $\displaystyle bleaching : powder$.

Bleaching powder loses ___________ by the action of dilute acids in excess.

  1. oxygen

  2. calcium

  3. chlorine

  4. water


Correct Option: C
Explanation:

Reaction of bleaching powder with $dil.HCl$:

$CaOCl _2 + 2HCl \rightarrow CaCl _2 + Cl _2 + H _2O$  

On long standing, bleaching powder undergoes auto-oxidation into:

  1. $Ca(ClO _3) _2, CaCl _2$

  2. $CaO, CaCl _2$

  3. $CaClO, CaClO _3$

  4. $CaClO _2, CaCl _2$


Correct Option: A
Explanation:

On long standing, bleaching powder undergoes auto-oxidation into calcium chlorate $Ca(ClO _3) _2$ and $ CaCl _2$.
 $6CaOCl _2 \rightarrow 6 Ca(ClO _3) _2  + 5 CaCl _2$.
The bleaching powder is $CaOCl _2$

Uses of bleaching powder is/are:

  1. It is used as a disinfectant in sterilization of water

  2. It is used to bleach straw, ivory

  3. It is used as an oxidising agent in industry

  4. It is used for making wool unshrinkable


Correct Option: A,C,D
Explanation:

Following are the uses of bleaching powder.
(A) It is used as a disinfectant in sterilization of water
(C) It is used as an oxidising agent in many chemical reactions in industry
(D) It is used for making wool unshrinkable
Bleaching powder is useful in preparation of organic solvent chloroform which is also used as an anesthetic.
Bleaching action is possible on cotton in textile industry, wood pulp in paper factories and washed clothes in laundary.

Bleaching powder loses oxygen in the presence of:

  1. calcium chloride

  2. cobalt chloride

  3. sodium chloride

  4. none of the above


Correct Option: B
Explanation:

Bleaching powder loses oxygen in the presence of  cobalt chloride catalyst.
$2CaOCl _2 \xrightarrow {CoCl _2} 2CaCl _2 + O _2$

The colour of bleaching powder is :

  1. green

  2. pale yellow

  3. blue

  4. white


Correct Option: B
Explanation:

Bleaching powder is a yellowish white powder which gives a strong smell of chlorine.

When treated with $conc. HCl, MnO _{2}$ yields a gas $(X)$ which further reacts with $Ca(OH) _{2}$ to generate a white solid $(Y)$. The solid $Y$ reacts with $dil. HCl$ to produce the same gas $X$. The solid $Y$ is :

  1. $CaO$

  2. $CaCl _{2}$

  3. $Ca(OCl)Cl$

  4. $CaCO _{3}$


Correct Option: D
Explanation:
X : Carbon dioxide              $CaCO _3+HCl  \rightarrow CaCl _2+ H _2O+CO _2$     
Y : Calcium Carbonate      $Ca(OH) _2 + CO _2 \rightarrow CaCO _3 + H _2O$
Z : $Ca(HCO _3) _2$                    $CaCO _3+H _2O+CO _2\rightarrow Ca(HCO _3) _2$

Bleaching powder is used for disinfecting drinking water.

  1. True

  2. False


Correct Option: A
Explanation:

Bleaching powder, $CaOCl _2$ or calciumoxychloride is used to kill germs and bacteria of water because it contains chlorine element, which is good disinfecting agent.