Foxing refers to the appearance of reddish-brown or brown spots on old paper. It is believed to be caused by the presence of iron or other metal impurities in the paper, which oxidize over time, or by the growth of fungi or bacteria in the presence of moisture and these impurities.
Foxing on paper is a - - (5) Question not attempted
Asked in Department Recruitment 2024 (Chemist) 2024 · Topic: Physical and Chemical Changes, Solution (Definition and Characteristics of Chemical Changes (Chemical Reactions))
Show answer
Answer: B. (2) Brown colour spot on paper
More Chemistry questions
- What is the recommended level of 'copper number' for the paper for permanent records? - (5) Question not attempted
- What is the duration for which ‘Accelerated Ageing Test’ conducted on paper? - (5) Question not attempted
- Why are non-aqueous methods used for de- acidifying certain documents? - (5) Question not attempted
- Hygrometer is used in the conservation laboratory for measuring - - Question not attempted
- Which of the following statements about chemical equilibrium is correct ? - At equilibrium, the system undergoes no net change. - At equilibrium, the forward and backward reactions cease to occur. - At equilibrium, the concentrations of reactants and products are equal. - The catalysts, shift the position of the equilibrium.
- Corrosion of metals involves -
- Match the following reactions with their types and choose the correct option : Reaction Type of Reaction a. Decomposition CaO + H2O → Ca(OH)2 (i) reaction CaCO3 $\xrightarb. Displacement (ii) row{\Delta}$ CaO + reaction CO2 Pb + CuCl2 → PbCl2 + c. Combination (iii) reaction Cu d. Double dis‐ Na2SO4 + BaCl2 → (iv) placement reac‐ BaSO4 + 2NaCl tion Codes : (i) (ii) (iii) (iv) (1) a b c d (2) a c b d (3) c a b d (4) c b d a (5) Question not attempted
- Pb(s) + CuCl₂(aq) → PbCl₂(aq) + Cu(s) The above reaction is an example of -