Anil is a laboratory assistant in a college. He prepared nitric acid but stored it in a transparent container exposed to sunlight. After a few days, brown fumes were observed in the container and the acid turned slightly yellowish in colour.
(a) What was the error made by Anil while storing the acid?
(b) Why were brown fumes observed in the container?
(c) How can the yellowish tinge in the acid be removed?
Anil is a laboratory assistant in a college. He prepared nitric acid but stored it in a transparent container exposed to sunlight. After a few days, brown fumes were observed in the container and the acid turned slightly yellowish in colour.
(a) What was the error made by Anil while storing the acid?
(b) Why were brown fumes observed in the container?
(c) How can the yellowish tinge in the acid be removed?
Show Hint
Solution and Explanation
(a) Storage Error: Anil should have stored the nitric acid in an amber-colored (dark) bottle and kept it in a cool, dark place away from sunlight.
(b) Thermal Decomposition: Nitric acid is unstable in the presence of heat or sunlight. It decomposes to give nitrogen dioxide (NO_2), which appears as brown fumes and dissolves in the remaining acid to give it a yellow tint. [ 4HNO_3 xrightarrowtextsunlight 4NO_2 uparrow + O_2 uparrow + 2H_2O ]
(c) Removal of Yellow Tinge: The yellow color can be removed by bubbling dry air or carbon dioxide through the acid (to drive out the dissolved NO_2) or by adding a small amount of water.
Top Questions on Periodic Table
Which of the following element pairs will form an ionic bond?
- ICSE Class X board - 2026
- Chemistry
- Periodic Table
- The electronic configuration of an element is 2,8,2. The hydroxide of this element can produce ______ hydroxyl ions per molecule.
- ICSE Class X board - 2026
- Chemistry
- Periodic Table
- An atom of X forms an ion according to the equation ( X + 2e^- X^2- ). The atomic number of the atom X is:
- ICSE Class X board - 2026
- Chemistry
- Periodic Table
- Element A belongs to group 15 and period 2 of the Periodic Table.
(a) Identify the element A.
(b) Write the formula of the compound formed when element A combines with hydrogen.
(c) Draw the dot (●) and cross (×) structure of the compound formed in (b) above.
- ICSE Class X board - 2026
- Chemistry
- Periodic Table
State whether the following statements are True or False.
(a) Organic compounds having different molecular formula, but same structural formula are called isomers.
(b) A salt is a compound formed by partial or complete replacement of the hydrogen ion of an acid by a metal or electropositive ion.
- ICSE Class X board - 2026
- Chemistry
- Periodic Table
Questions Asked in ICSE Class X board exam
- (a) Name the electromagnetic radiation used to detect fake currency.
(b) Redraw the diagram given below and complete the path of the light ray AB through the glass prism till it emerges out of the prism. Critical angle of the glass is 42\(^\circ\).
- ICSE Class X board - 2026
- Refraction of Light
- A monochromatic ray strikes the surface of identical prisms (A, B and C) at different angles of incidence. The diagram below shows their refracted rays. Study the path of these refracted rays and identify in which of the diagrams
(a) the angle of incidence is maximum.
(b) the angle of incidence is minimum.
(c) the angle of incidence is equal to the angle of emergence.
- ICSE Class X board - 2026
- Refraction of Light
- For a body to be in dynamic equilibrium, its:
- ICSE Class X board - 2026
- laws of motion
Given below is the industrial process for the manufacture of ammonia gas. Study the schematic diagram to answer the following questions.
(a) Name the process.
(b) Which catalyst is used in the above process?
(c) In the above diagrammatic setup, how is ammonia gas separated from the unreacted gases to obtain liquid ammonia?
(d) Which two properties of ammonia gas can be demonstrated by the Fountain Experiment?
- ICSE Class X board - 2026
- Occurrence Of Metals
(a) Give the IUPAC name for the following organic compounds:
- ICSE Class X board - 2026
- Organic Chemistry