1)¿Cuáles son los sentidos comunes que se pueden utilizar, para identificar un metal, gases o líquido?

The question is another language. Translation in English language is as following:

What are the common sensors that can be used to identify metal, gas or liquid?

Common sensors that can be used to identify metal, gas or liquid are as following:

Inductive Proximity Sensor: Inductive proximity sensors are able to detect metals only. It generates output signal or electrical signal when any metal object come nearby its sensing area.Handheld flammable gas detectors: they are commonly used to detect gas leakage such as natural gas lines, butane tanks, or any other combustible gas.Optical level sensors: this sensor is used to detect liquids including the interface between two immiscible liquids and the occurrence of sediments.

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