Question

Assertion: Calcium bisulfite is used in the paper industry.
Reason: Metallic sulphites show strong bleaching action.
(A) Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion.
(B) The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.
(C) Our Assertion is true but the Reason is false.
(D) The statement of the Assertion is false but the Reason is true.

Answer 1

Hint :Bleaching wood pulp is the chemical process of lightening and whitening the pulp's colour. Paper is the major product of wood pulp, and whiteness (which is comparable to but not the same as brightness) is a significant quality. These methods and chemistry can also be used to bleach non-wood pulps like bamboo or kenaf.

Complete Step By Step Answer:
By processing wood chips with sulfite and bisulfite ion solutions, the sulfite method creates near pure cellulose fibres. These compounds break the links between the lignocellulose's cellulose and lignin components. Sodium ($N{a}^{+}$), calcium ($C{a}^{2+}$), potassium ($K^{+}$), magnesium (Mg^{2+}), and ammonium (${N{H}_4}^{+}$) are among the sulfite/bisulfite salts utilised. Lignin is transformed to lignosulfonates, which are soluble and separate from the cellulose fibres. The sulfite method competes with the Kraft method for the manufacturing of cellulose, which yields stronger fibres and is less ecologically friendly.
Paper chemicals refer to a set of chemicals that are used in the production of paper or that alter the characteristics of paper. These chemicals may be used to modify the paper in a variety of ways, such as modifying its colour and brightness, as well as enhancing its strength and water resistance. White paper is made by bleaching wood pulp to eliminate any colour from trace quantities of lignin that were not recovered during the chemical pulping process.
Hence option A is correct.

Note :
To retain a specified writing quality and printability, most paper types must have some water resistance. Until 1980, the most common method of increasing resistance was to use rosin in conjunction with alum. When the paper industry decided to use chalk instead of china clay as a filler, the chemistry of the paper had to change. AKD (alkyl ketene dimer) and ASA (alkenyl succinic anhydride) are the most common chemicals used nowadays.