How long does gunpowder residue remain on a shooter's hands?
a few hours
about 24 hours
a few days
about a week

A few hours

Explanation:

A gunshot residue is a powdery discharge of a firearm which consists of unburned or partially burned primer and propellent mixers which are used in the cartridge case to propel out the projectile with force exerted by the gases produce after burning of the powder charge. This residue gets deposit over the hands of the shooter, clothes of the shooter or the target and the nearby firing region.

The gunshot residue remains for few hours on a shooter's hand. The powder discharge can easily be cleaned and this can be collected by using tape, swabing or by washing the hands with suitable solvents.

answer: - few nutrients

high pressure

low temperatures

explanation: 1. few nutrients:   open-ocean zone is located way far from the land, which is the main source of the essential nutrients.2. high pressure: pressure increases by 1 atmosphere for every 10 meters increase in depth.3. ample sunlight: a large fraction of the sunlight is reflected back to the atmosphere from the sea surface. 4. varying salinity: below the thermocline, the water is isolated from the atmosphere so the salinity remains stable over the year.5. low temperatures:   the temperature of open-ocean zone ranges from a low of -2°c to an average of 17°c