The chemical used as a ‘fixer’ in photography is
Reviewed by Dalvoy
UPSC Civil Services preparation
- Asodium sulphate
- Bsodium thiosulphateCorrect
- Cammonium persulphate
- Dborax
Explanation
The correct option is B because sodium thiosulphate, traditionally known as hypo, has the specific chemical property of dissolving silver halides. During the photographic development process, some silver bromide remains unexposed on the film. If left there, it would blacken over time and ruin the image. Sodium thiosulphate reacts with this unexposed silver bromide to form a soluble complex, which is then washed away. This process fixes the image permanently on the film or paper, preventing further chemical reactions when exposed to light.
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