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

Powdered sulphur is heated. It is introduced into a glass jar and covered with a lid. Now, water is added into the jar, lid is placed again and then is shaken well. When a blue litmus is introduced into this jar, it turns red. Which of the following is present inside the jar?

  1. Nitric acid

  2. Hydrochloric acid

  3. Sulphurous acid

  4. Copper sulphate

  5. Magnesium sulphate
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

On heating, sulphur burns to produce sulphur dioxide. This reacts with water to form sulphurous acid.

Multiple choice

A teacher demonstrates the following experiment in the lab. Zinc pellets are added to a blue-coloured solution. When kept for some time, the blue colour vanishes and a colourless solution is formed in which a red mass is lying. The teacher tells the students that the colourless solution is zinc sulphate and the red mass is copper. What was the original blue-coloured solution?

  1. Copper sulphate

  2. Copper oxide

  3. Copper carbonate

  4. Zinc oxide

  5. Zinc carbonate
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The original blue-coloured solution was copper sulphate.

Multiple choice

The metal in compound F imparts which color to the flame?

A white coloured compound A on heating gives a gas C and a solid residue B. C on reaction with RMgX gives carboxyilic acid. B on reaction with water gives D which on reaction with H2O2 gives E through formation of an intermediate compound. E on reaction with dil. HCl gives F and hydrogen peroxide. F is used for removing ice on the roads. F on reaction with sulfuric acid gives G and an acid.

  1. Burgundy red

  2. Brick red

  3. Apple green

  4. Crimson red

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The metal in F is calcium, and it imparts brick red color to the flame.

Multiple choice

Which statement(s) is/are true?

  1. M2SO4.10H2O is known as Glauber's salt.
  2. Carbonate of metal M is used as an antacid.
  3. Cooling M2SO4.10H2O below 285K results in M2SO4.3H2O.

    When a metal M is heated in excess of air, it gives two products A and B. A is pale blue in colour. B on reaction with liquid ammonia gives C. B on rection with water produces D. B  dispropotionates to A on heating at 670K.

  1. 1, 2, 3

  2. 1, 2

  3. 1, 3

  4. 2, 3

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

 Statement 3 is wrong besause cooling M2SO4.10H2O below 285K results in M2SO4.7H2O.

Multiple choice

What are the reddish brown precipitates found at the bottom of the beaker, when a beaker containing copper sulphate solution and a few iron nails is left for sometime?

  1. Copper

  2. Iron

  3. Copper sulphate

  4. Iron sulphate

  5. Mixture of copper and iron
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When iron nails are kept in a beaker containing copper sulphate solution, the displacement reaction takes place. As iron is more reactive than copper, it displaces copper from the copper sulphate solution. The iron nail becomes brownish in colour and the blue colour of copper sulphate solution fades. Thus, it becomes iron sulphate and copper. This copper is reddish brown in colour and precipitated at the bottom of the beaker.

Multiple choice

Which of the following is not a property of SO2?

  1. It decolourises bromine water.

  2. It turns acidified potassium dichromate solution green.

  3. It turns potassium permanganate solution pink.

  4. It bleaches the colour of a wet flower.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

SO2 turns potassium permanganate solution pink.

Multiple choice

Which among the basic concepts of green chemistry evaluates the efficiency of chemical transformation?

  1. Prevent Waste

  2. Maximize atom economy

  3. Design of safer chemicals

  4. Increase energy efficiency
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This option is correct because it evaluates the efficiency of chemical transformation. Similar to yield calculation, atom economy is a ratio of total mass of atoms in desired product to the total mass of atoms in the reactants. Hence it evaluates the efficiency of chemical transformation.

Multiple choice

Which of the following statements is/are incorrect?

P. CuCl2 is used as a catalyst in the manufacture of ammonia by Haber process. Q. CuCl exhibits blue colour in aqueous solution.
R. Fractional crystallisation of metals to get maximum pure form is known as zone refining.

  1. Only P

  2. Only Q

  3. Only R

  4. P and Q

  5. Q and R
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This option is correct because iron (Fe) is used as a catalyst in the manufacture of ammonia by Haber process, while CuCl2 is used as a catalyst in Deacon process for the preparation of Cl2 from HCl. CuCl in aqueous solution form Cu+ ions, which possess no colour due to the presence of completely filled d orbitals.

Multiple choice

Which of the following statements is correct?

  1. SO2 acts as temporary bleaching agent, while Cl2 acts as permanent bleaching agent.

  2. SO2 acts as permanent bleaching agent, while Cl2 acts as temporary bleaching agent.

  3. Both SO2 and Cl2 act as temporary bleaching agents.

  4. Both SO2 and Cl2 act as permanent bleaching agents.

  5. SO2 can be used as bleaching agent, while Cl2 cannot be used.<!--?xml:namespace prefix = o /--><o:p></o:p><o:p></o:p>
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

SO2 bleaches due to reduction which is temporary bleach and can be converted to its original by atmospheric oxygen, whereas Cl2 bleaches due to oxidation which is permanent bleach.