Which metal bromide is widely used in photography?

Step 1: Analyze the question The question asks which metal bromide is widely used in photography.

Step 2: The concept Photography (traditional film and photographic paper) relies on light-sensitive silver halides. When light hits silver bromide (AgBr), it decomposes and produces silver metal:

2AgBr → 2Ag + Br₂ (in the presence of light)

The tiny deposits of silver form a latent image, which is then developed into the visible black-and-white image. Silver bromide is coated as an emulsion in gelatin on film and photographic paper.

Step 3: Check the options

• A. Calcium bromide: not light-sensitive, so it is not used for photographic film.
• B. Magnesium bromide: not used in photography.
• C. Potassium bromide: used in photography only as a restrainer in developers. It is not the light-sensitive material, so it is not the best answer.
• D. Silver bromide: the light-sensitive compound in photographic film and paper.
• E. Sodium bromide: used mainly as a sedative or in chemical processes, not as the light-sensitive agent.

Step 4: Answer The correct option is D. silver bromide.

Tip: Remember "silver halides = photography." AgBr, AgCl and AgI all darken in light. In the same way, AgCl is used in photographic paper and AgNO₃ is stored in dark bottles. Whenever you see "photography" in an exam, think silver.