(dissolving or reacting) . All gases are less dense than liquid water and will displace the water downwards. No good for soluble gases like ammonia, hydrogen chloride, nitrogen dioxide or sulphur dioxide. You can collect in inverted gas jar if bigger sample required.You have to watch for 'sucking back' effects. Answer   Hydrogen can be collected by the downward displacement of water because of two reasons: it is less dense than water, and so rises to the surface, and it â¦ is not very soluble in water, and so nearly all the gas can be collected because very little is dissolved in the water.
preserve - a domain that seems to be specially reserved for someone; medicine is no longer a male preserve. 1  arena, domain, sphere, orbit, area, field - a particular environment or walk of life; his social sphere is limited; it was a closed area of employment; he's out of my orbit.
Preserves are foods such as jam that are made by cooking fruit with a large amount of sugar so that they can be stored for a long time. If you say that a job or activity is the preserve of a particular person or group of people, you mean that they are the only ones who take part in it.