Chemistry

Chemical Reactions and Processes

626 Questions

Chemical reactions and processes questions cover the transformation of substances through electrolysis, thermal decomposition, and catalysis. Key areas include identifying gas evolution, balancing chemical equations, and understanding industrial chemical applications. This general chemistry topic is a staple in the science sections of multiple competitive examinations.

Thermal decompositionElectrolysis processGas evolution reactionsHeterogeneous catalystsFuel cell components

Chemical Reactions and Processes Questions

Multiple choice

What happens when copper chloride is electrolysed?

  1. Copper chloride is broken down to form copper.

  2. Chlorine gas is formed.

  3. It turns black in colour.

  4. Both 1 and 2
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

If electricity is passed through a copper chloride solution, copper chloride is broken down to form copper metal and chlorine gas. Positively charged ions move to the negative electrode during electrolysis.

Multiple choice

When vanaspati oil reacts with hydrogen, it gets converted into vanaspati ghee. In this process, the catalyst used is

  1. Fe

  2. Mo

  3. V

  4. Ni
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Nickel (Ni) is used as a catalyst in the hydrogenation of vanaspati oil to convert it into vanaspati ghee. This process adds hydrogen to the double bonds in unsaturated fatty acids, making them more saturated and solid at room temperature. Nickel provides an effective catalytic surface for hydrogen addition under moderate temperature and pressure conditions.

Multiple choice

Solvay process cannot be extnded to manufacture of K2CO3 because of

  1. high heat of formation of K2CO3

  2. high solubility of K2CO3 in solution

  3. low hydration enthalpy of K+ ion

  4. low ionisation enthalpy of K2CO3
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This option is correct because of the high solubility of K2CO3 in solution it cannot be precipitated out as Na2CO3 and hence solvay process cannot be employed for the formation of K2CO3

Multiple choice

Mercury tree is formed by

  1. pouring mercury into silver nitrate solution

  2. heating of Hg with current chlorine

  3. reaction of ammonia with HgCl2

  4. reaction of HgCl2 with excess of potassium iodide

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

This option is correct because when a little amount of mercury is poured into silver nitrate solution, a tree-like growth of silver amalgam is produced called mercury tree.

Multiple choice

Which of the following statements does not describe physical change?

  1. Composition of substance remains same.

  2. No new substance is formed.

  3. Chemical properties of a substance change.

  4. Physical changes are reversible.

  5. Expansion of iron on heating is an example of physical change.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Yes, it is the correct answer as properties are changed in the chemical changes, not physical changes.

Multiple choice

What happens during a chemical change?

  1. There is no change in composition.

  2. A substance combines with other to form a new substance.

  3. There is no change in molecular composition.

  4. Energy is always given out.

  5. There is no change in colour.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Chemical change lead to the formation of new substance.

Multiple choice

Which group of changes include only chemical changes?

  1. Metabolism of food in the body, electroplating a metal and crushing a can

  2. Mixing an acid and a base, baking a cake and breaking a glass

  3. Mixing an acid and a base, baking a cake, and electroplating a metal

  4. Electroplating a metal, baking a cake and crushing a can

  5. Metabolism of food in the body, burning a candle and electroplating a metal
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

All are the types of chemical changes.

Multiple choice

Which of the following statements regarding nitric acid are TRUE? P. Nitric acid is a colorless and odorless fuming liquid. Q. Nitric acid is produced commercially by Ostwald process. R. Nitric acid decomposes in sunlight to form nitrogen monoxide, water and oxygen. S. The common laboratory reagent known as concentrated nitric acid contains 70.4% HNO3 by mass.

  1. P and Q

  2. P and R

  3. Q and R

  4. Q and S

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

Nitric acid is produced commercially by the oxidation of ammonia in the Ostwald process. The common laboratory reagent known as concentrated nitric acid is 15.9 M HNO3 (70.4% HNO3 by mass).