Question

Which chemical is most commonly used for the development of latent fingerprints on porous surfaces like paper?

• A. Silver Nitrate
• B. Iodine
• C. Ninhydrin
• D. Cyanoacrylate

Hint:

{Ninhydrin} is the most commonly used chemical for developing latent fingerprints on {porous surfaces like paper}. It reacts with amino acids in sweat and produces a {purple-colored print}.

Answer 1

The Correct Option is C

Concept: Latent fingerprints are invisible or barely visible prints left on surfaces by the natural oils and sweat from the skin. These prints often require chemical methods to become visible. Different chemicals are used depending on the type of surface:

• Powder methods – for non-porous surfaces like glass or metal.
• Cyanoacrylate (super glue) – for plastic and smooth surfaces.
• Chemical reagents – for porous surfaces such as paper.

Step 1: Understanding porous surfaces.
Porous surfaces include materials that absorb liquids, such as:

• Paper
• Cardboard
• Raw wood

Fingerprints on these surfaces are absorbed into the material and cannot be easily developed using normal powder techniques.
Step 2: Identifying the chemical used for development.
The chemical Ninhydrin reacts with amino acids present in sweat residues of fingerprints. This reaction produces a deep purple color known as Ruhemann's Purple, which makes the latent fingerprint visible. Thus, the correct answer is: \[ \boxed{\text{Ninhydrin}} \]