List of top Chemistry Questions on Periodic Table asked in ICSE Class X board

Bauxite is the principal ore used in the commercial extraction of aluminium. The Bayer’s process is used to refine bauxite into pure alumina, with caustic soda playing a crucial role in the initial stage of the process. Based on this, answer the following questions: 

(a) Explain the reason behind the addition of caustic soda during the Bayer’s process. 
(b) Write a balanced chemical equation representing the reaction between bauxite and caustic soda during the Bayer’s process. 
 

Carbon reacts with an acid to form carbon dioxide, water and nitrogen dioxide.
(a) Name the acid used in the reaction.
(b) Write a balanced chemical equation for the reaction that occurs.

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? 
 

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. 
 

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.
An atom of X forms an ion according to the equation ( X + 2e^- X^2- ). The atomic number of the atom X is:
The electronic configuration of an element is 2,8,2. The hydroxide of this element can produce ______ hydroxyl ions per molecule.

Which of the following element pairs will form an ionic bond?