Directions: The following items consist of two statements, Statement I and Statement II. You are to examine these two statements carefully and select the answers to these items using the code given below: Statement I: Colour of Nitrogen dioxide changes to colourless at low temperature. Statement II: At low temperature Nitrogen tetroxide (N 2O 4) is formed which is colourless.
Both the statements are individually true and Statement II is the correct explanation of statement I
Understanding Nitrogen Dioxide Colour Change with Temperature
The question asks us to analyze two statements regarding the behaviour of Nitrogen dioxide (NO₂) gas at low temperatures and determine the relationship between them.
Analyzing Statement I: Colour Change of Nitrogen Dioxide
Statement I says that the colour of Nitrogen dioxide changes to colourless at low temperature. Nitrogen dioxide (NO₂) is known to be a reddish-brown coloured gas at room temperature. When the temperature is lowered, a visible change is observed: the brown colour fades and eventually becomes colourless or very pale yellow at sufficiently low temperatures.
This statement is factually correct. The colour of the system containing nitrogen oxides changes with temperature, becoming less intense brown as temperature decreases.
Analyzing Statement II: Formation of Nitrogen Tetroxide
Statement II says that at low temperature, Nitrogen tetroxide (N₂O₄) is formed, and it is colourless. Nitrogen dioxide (NO₂) exists in equilibrium with its dimer, Nitrogen tetroxide (N₂O₄).
The chemical reaction representing this equilibrium is:
\(2 \text{NO}_2\text{(g)} \rightleftharpoons \text{N}_2\text{O}_4\text{(g)}\)
Nitrogen dioxide (\(\text{NO}_2\)) is a brown gas. Nitrogen tetroxide (\(\text{N}_2\text{O}_4\)) is a colourless gas/solid.
This dimerization reaction is exothermic, meaning it releases heat (\(\Delta H < 0\)). According to Le Chatelier's principle, for an exothermic reaction, lowering the temperature shifts the equilibrium position towards the products. In this case, lowering the temperature favours the formation of \(\text{N}_2\text{O}_4\).
Therefore, at low temperatures, a significant amount of the brown \(\text{NO}_2\) gas converts into colourless \(\text{N}_2\text{O}_4\) gas. This statement is also factually correct.
Connecting Statement I and Statement II
Statement I describes the observation: the system becomes colourless at low temperature. Statement II provides the reason: at low temperature, colourless \(\text{N}_2\text{O}_4\) is formed. Since the brown \(\text{NO}_2\) is converting into colourless \(\text{N}_2\text{O}_4\) at low temperatures, the overall system appears colourless. Thus, the formation of colourless \(\text{N}_2\text{O}_4\) (Statement II) directly explains why the brown colour disappears (Statement I) at low temperatures.
Both statements are true, and Statement II provides the correct explanation for Statement I.
Conclusion
Based on the analysis of both statements and their relationship, we conclude that Statement I is true, and Statement II is true, and Statement II correctly explains Statement I.
Similar Questions
Directions: The following items consist of two statements, Statement I and Statement II. You are to examine these two statements carefully and select the answers to these items using the code given below:
Statement I: Oxygen gas is easily produced at a faster rate by heating a mixture of Potassium Chlorate and Manganese dioxide than heating Potassium chlorate alone.
Statement II: Manganese dioxide acts as a negative catalyst.
Which one of the following is a chemical change?
Directions: The following items consist of two statements, Statement I and Statement II. You are to examine these two statements carefully and select the answers to these items using the code given below:
Statement I: The granules of modern gunpowder (also called black powder) are typically coated with Graphite.
Statement II: Graphite prevents the build-up of electrostatic charge.
- Which one of the following is not an example of a redox reaction?
- Which one of the following is not a pigment?
- Which one of the following reactions is an example of decomposition reaction?
Which among the following is the correct arrangement of halogens in the increasing order of their oxidizing nature?
An iron nail dipped in copper sulphate solution turns brown. This is due to which one of the following types of reactions?
Copper sulphate crystals available in the market are blue coloured crystals. By careful heating, they turn to white colour. Which one of the following is responsible for the blue colour?
Which one of the following species is NOT capable of showing disproportionation reaction?
Important Questions from Chemical Reaction
Which of the following statement is/are true?
I. In physical change new substance is formed. substance is formed.
II. In chemical change no new substance is formed.
Which of the following cells involves similar chemical reactions?
The information not obtained from balanced chemical equation is
Oxygen cannot be obtained by which one of the following methods?
Which is the most reactive metal?
