Provide a systematic name of the following compound below: 3 ethyl 2-5- dimethyl- 4 propylheptane

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Is a pencil falling to the floor anon contact force, a force, or a contact force

Alidded glass container is filled with a colored gas. after a period of time, it is observed that the gas is uniformly spread throughout the box and that the movement has slowed considerably. next, a warm iron plate is carefully placed under the box. why is there resumed movement of the gas in the container?