Chemistry

Chemical Reactions and Processes

571 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

Which of the following is used to dissolve noble metals?

  1. Nitric acid

  2. Hydrochloric acid

  3. Sulphuric acid

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

Aqua regia (Latin for 'royal water') is a mixture of nitric acid and hydrochloric acid in 1:3 ratio. It can dissolve gold and platinum, which are 'noble' metals that resist most other acids. The chloride ions form soluble complexes with noble metal ions.

Multiple choice

Which of the following statements is/are false?

a. Rain water dissolves carbon dioxide gas from air and forms carbonic acid. b. The aqueous solution of an acid conducts electricity due to the presence of charged particles in it. c. Acids show acidic behaviour in the absence of water.

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

  5. Only c
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This is the correct option as this statement is false. Acids do not show acidic behaviour in the absence of water.

Multiple choice

Many of the transition metals behave as catalysts, either as the metal itself or as a compound. Which of the following pairs does not match correctly the transition metal catalysts with the chemical process catalysed by them?

  1. V2O5: Contact process

  2. Fe: Haber process

  3. Raney Nickel: Catalytic hydrogenation

  4. TiCl4: Reduction of alkenes

  5. Ziegler-Natta-polymerisation of ethene
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Raney nickel, which is very finely divided nickel powder, is a catalyst for the addition of hydrogen across C=C and C≡C bonds.

Multiple choice

Ammonia is the starting material for nitric acid manufacture.The solution of ammonia in water is known as

  1. ammonium chloride

  2. ammonium sulfate

  3. ammonium nitrate

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

Ammonium hydroxide is a solution of ammonia in water. It can be denoted by the symbols NH3(aq). Although the name ammonium hydroxide suggests a base with composition [NH4+][OH−], it is actually impossible to isolate samples of NH4OH. These ions only comprise a tiny fraction of ammonia.

Multiple choice

Which of the following is not a property of a base?

  1. Bases have bitter taste.

  2. Bases feel soapy to touch.

  3. Bases turn red litmus to blue.

  4. Bases react with some metals to form hydrogen gas.

  5. Bases react with metal oxides to form salt and water.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This is the correct option as this is not a property of a base. Bases react with non-metal oxides to form salt and water.

Multiple choice

The potassium hydroxide acts as a electrolyte in

  1. a nickel-cadmium battery

  2. a nickel hydrogen battery

  3. a nickel-metal hydride cell

  4. a nickel-iron battery
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The nickel-iron battery (NiFe battery) is a storage battery having a nickel(III) oxide-hydroxide cathode and an iron anode, with an electrolyte of potassium hydroxide. The active materials are held in nickel-plated steel tubes or perforated pockets.

Multiple choice

Among the following compounds -------------------- releases HF upon exposure to water.

  1. sulphur tetrafluoride

  2. xenon difluoride

  3. xenon hexafluoride

  4. nickel(II) fluoride
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sulphur tetrafluoride is the chemical compound. This species exists as a gas at standard conditions. It is a corrosive species that releases dangerous HF upon exposure to water or moisture. Despite these unwelcome characteristics, this compound is a useful reagent for the preparation of organofluorine compounds, some of which are important in the pharmaceutical and chemical industries.

Multiple choice

The reagent capable of transferring hydrides to metal centers is

  1. polymethylhydrosiloxane

  2. polydimethylsiloxane

  3. potassium bis(trimethylsilyl)amide

  4. potassium tert-butoxide

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Polymethylhydrosiloxane (PMHS) is a polymer with the general structure -(CH3(H)Si-O)-. It is used in organic chemistry as a mild and stable reducing agent, easily transferring hydrides to metal centers.