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

Prismatic sulphur is formed by

  1. bubbling air through molten sulphur

  2. allowing molten sulphur to crystallise slowly in contact with hot molten sulphur

  3. passing an electric arc through sulphur vapour

  4. cooling molten sulphur quickly with water
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

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Multiple choice

Compounds may be formed by

  1. decomposition of other compounds

  2. combination of elements

  3. combination of compounds

  4. all of the above methods
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

There are various ways by which compounds can be formed, like by the decomposition of other compounds, combination of elements and combination of compounds.

Multiple choice

Chlorine gas used for disinfection combines with water to form hypochlorous acid (HOCl). HOCl ionizes to form hypochlorite (OCl-) in a reversible reaction: HOCI $\Leftrightarrow$ H+ + OCl- (k= 2.7 × 10-8 at 20 oC), the equilibrium of which is governed by pH. The sum of HOCI and OCl- is known as free chlorine residual and HOCI is the more effective disinfectant. The 90% fraction of HOCl in the free chlorine residual is available at a pH value

  1. 4.8

  2. 6.6

  3. 7.5

  4. 9.4
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The fraction of HOCl is given by 1 / (1 + K/H+). For 90% (0.9) fraction, 0.9 = 1 / (1 + 2.7e-8 / H+). Solving for H+ gives H+ = 2.43e-7, and pH = -log(H+) = 6.61.

Multiple choice chemistry non-metals dihydrogen fuel dihydrogen as a fuel introduction to hydrogen

Hydrogen can be prepared on commercial scale by different methods. In its preparation by the action of steam on hydrocarbons, a mixture of $CO$ and $H _2$ gas is formed called:

  1. water gas

  2. syngas

  3. producer gas

  4. industrial gas
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Mixture of $CO$ and ${ H } _{ 2 }$ is called water gas. As the mixture of $CO$, $CO _2$ and ${ H } _{ 2 }$ is used for the synthesis of methanol and a no. of hydrocarbon, it is also called synthesis gas or 'syngas'.