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 zinc is dissolved in sulphuric acid?

  1. Nitrogen will be liberated.

  2. There will not be any reaction between zinc and sulphuric acid.

  3. Oxygen will be liberated.

  4. Zinc will replace hydrogen in the sulphuric acid to form zinc sulphate.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Zinc is more reactive than hydrogen, so it displaces hydrogen from sulphuric acid, resulting in the formation of zinc sulphate and hydrogen gas.

Multiple choice

Which of the following happens when metals are treated with hydrogen?

  1. Metals do not react with hydrogen.

  2. Metal hydrides are formed with the evolution of heat.

  3. Metal hydrides are formed with the absorption of heat.

  4. Metal hydroxides are formed with the evolution of heat.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When metals react with hydrogen, they form metal hydrides. This reaction is typically exothermic, meaning it releases heat.

Multiple choice

The compound used for storing hydrogen in hydrogen tanks is

  1. sodium aluminium hydride

  2. sodium aluminium phosphate

  3. sodium aluminium sulphate

  4. sodium hexafluoroaluminate
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sodium aluminium hydride (NaAlH4) or sodium alanate is a chemical compound used as a reducing agent. It is similar to lithium aluminium hydride. It is used for hydrogen storage in hydrogen tanks.

Multiple choice

Which of the following statements is/are not true about the diagonal relationship of Be and Al?

(A) Both react with NaOH to liberate hydrogen. (B) Their oxides are basic. (C) They are made passively by nitric acid. (D) Their carbides give acetylene on treatment with water.

  1. Only (A)

  2. (B) and (C)

  3. Only (D)

  4. (B) and (D)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Oxides of Be and Al are amphoteric in nature. Their carbides give methane on treatment with water.

Multiple choice

Why do dry leaves catch fire more easily than green leaves?

  1. The dry leaves have high ignition temperature.

  2. The dry leaves have a lower ignition temperature.

  3. The dry leaves contain moisture which helps in burning.

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

The dry leaves have a lower ignition temperature and they do not have any moisture. So, they can burn easily.

Multiple choice

Water is used to extinguish fire because water

  1. raises the ignition temperature of the burning substance

  2. lowers the ignition temperature of the burning substance

  3. cools the burning substance to a temperature below its ignitions temperature

  4. conducts the heat
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When water is poured over the burning substance water absorbs heat from the substance. Because of this the temperature of burning substance falls below its ignition temperature and it stops burning.