I am pretty sure it is A because you could use a test tube or beaker filled with water and turn it upside down in another container filled with water and then use a hose or something to let the gas into the test tube to displace the water.You can't have use a gas that is soluble in water. am pretty sure it is A because you could use a test tube or beaker filled with water and turn it upside down in another container filled with water and then use a hose or something to let the gas into the test tube to displace the water.
verb (used with object), preserved, preserving. 1. to keep alive or in existence; make lasting: to preserve our liberties as free citizens. 2. to keep safe from harm or injury; protect or spare. 3. to keep up; maintain: to preserve historical monuments.
Definition of reserve for English Language Learners. : 1  to make arrangements so that you will be able to use or have (something, such as a room, table, or seat) at a later time. : 2  to keep (something) for a special or future use. : 3  to choose to do (something) at a later time.