Chemistry

Chemical Compounds and Reactions

505 Questions

Chemical compounds and reactions involve understanding the properties, colors, and formation of various chemical substances. Questions focus on identifying precipitates, observing color changes during reactions, and naming common compounds. This topic is a fundamental part of the chemistry syllabus for competitive exams.

identifying precipitateschemical reaction colorscompound namingcolloidal particle propertiesacid base reactions

Chemical Compounds and Reactions Questions

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

Bleaching powder is effective with cold water, but ineffective with hot water. This is because of:

  1. oxidation of chloride radical

  2. reduction of chloride radical

  3. reduction of hypochlorite radical

  4. hydrolysis of hypochlorite radical
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Bleaching action takes place due to the hypochlorite radical [$ClO^{-}$].

But when used in hot water, hot water favours reduction of the hypochlorite radical as a result of which bleaching powder is ineffective with hot water.
Generally, Bleaching powder is used as a disinfectant widely.

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

Bleaching powder is soluble in cold water giving a milky solution due to:

  1. available chlorine

  2. lime present in it

  3. calcium carbonate formation

  4. the absorption of carbon dioxide from atmosphere
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Bleaching powder on reaction with cold water form milky solution of calcium hydroxide. 

$CaOCl _2+H _2O\rightarrow Ca(OH) _2+Cl _2$

Thus because of the lime present in it, it gives a milky solution when dissolved in water.

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

Bleaching powder is obtained by the interaction of $Cl _2$ with a:

  1. dilute solution of $Ca(OH) _2$
  2. concentrated solution of $Ca(OH) _2$
  3. dry $CaO$

  4. dry slaked lime
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$Ca(OH) _2 +Cl _2 \rightarrow Ca(OCl)Cl + H _2O$
Bleaching powder is obtained by the interaction of $Cl _2$ with a dry slaked lime.

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

Bleaching powder slowly decomposes to form:

  1. $CaCl _2+Ca(ClO _3) _2$
  2. $CaO+Cl _2$
  3. $CaCl _2+Ca(OCl) _2$
  4. $CaCO _3+Cl _2$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When exposed to air, bleaching powder gives a smell of chlorine. This is because bleaching powder reacts with carbon dioxide from the atmosphere to produce calcium carbonate and chlorine.

$Ca(OCl) _2 +CO _2 \rightarrow CaCO _3 +Cl _2$

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

The amount of chlorine obtained from a sample of bleaching powder by treatment with excess of dilute acid or $ \displaystyle CO _{2}$ is called available chlorine.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The available chlorine is defined as the percentage of chlorine made available by bleaching powder when treated with dilute acids. The available chlorine present in bleaching powder sample is determined iodometricaliy by treating its solution with an excess of potassium iodide solution in the acidic medium.

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

Bleaching powder has a strong bleaching action due to:

  1. calcium

  2. chlorine molecule

  3. nascent oxygen

  4. chloride ion
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The bleaching powder has a strong bleaching action due to the formation of nascent oxygen.

When bleaching powder reacts with a small amount of acid, it gives nascent oxygen. 
Thus, it acts as an oxidizing agent and thus acts as a bleaching agent.

$2CaOCl _2 +H _2SO _4 \rightarrow CaCl _2+CaSO _4+2HOCl$

$2HOCl \rightarrow 2HCl+2[O]$

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

The real bleaching agent present in bleaching powder is:

  1. chlorine

  2. oxygen

  3. CaO

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Calcium oxychloride (CaOCl2) is known as bleaching powder. In the presence of small amount of dilute acid, it gives nascent oxygen which acts as an oxidising and bleaching agent. When it is treated with excess of dilute acids, chlorine is evolved which is responsible for the bleaching action of bleaching power.