Materials: A clean dry transparent glass jar (e. g., a jam bottle or a bigger bottle) Warm water Ice cubes Metal lid or a piece of metal (tray) to cover the mouth of the bottle.

steps : Fill a jar with 2 inches (5 cm) of warm water and stir. Then light a match, blow it out and quickly drop it into the jar. Immediately place an ice-filled metal tray or metal lid with ice on rop. Observe what happened for a couple of minutes. Lift the metal lid off the mouth of the Jar and observe what happens.

Questions:

(1) Why did you fill the jar with warm water and not cold water?

(2) What is the purpose of dropping a match that gives out smoke? What other materials can you use instead of a match?

(3) What is the purpose of placing a metal lid or tray with ice on top?

(4) What did you see inside the jar after a couple of minutes? Explain what happened inside the jar

(5) If the experiment were repeated. without a match producing smoke what would you expect to see? No thick cloud​

Scientist: cross-sections of stalactites—calcite formations deposited on cave ceilings by seeping water—can reveal annual variations in rainfall in particular areas over hundreds and thousands of years. we often found that when—according to these cross-sections—drought occurred in a particular area, it coincided with the collapse of an ancient society in that area. i hypothesize that drought reduced agricultural productivity in these areas, thereby leaving these societies without the resources needed to handle internal stresses and external threats. which of the following, if true, would most weaken the support for the scientist's hypothesis? a. many droughts indicated in the cross-sections of stalactites do not correspond with the collapse of a society in that area. b. information from the cross-sections of stalactites alone cannot reveal the level of agricultural output in an area at a particular time. c. most of the societies that collapsed during droughts did so when internal power struggles coincided with military raids from neighboring societies. d. most of the societies that collapsed during droughts maintained large stockpiles of food and water at the time of their collapse. e. information from stalactites also suggests that the collapse of some societies coincided with periods of abnormally high rainfall.