Answer is: reactivity series or activity series.
Reactivity series is an empirical progression of a series of metals, arranged by their reactivity from highest to lowest (alkaline metals have highest reactivity and Noble metals lowest reactivity). This series are used to summarize information about the reactions of metals with acids or water, double displacement reactions (more reactive metals displace metals with lower reactivity) and the extraction of metals from their ores.
The lone pair of electrons in Caffeine are shown in RED color in attached figure.
Details:
In chemistry there are two types of electrons.
i) Bonding Pair Electrons:
These are those electrons which are being shared and are involved in making bonds. They are also called as sharing electrons. In given structure all the solid bonds either single or double are made up of bonding pair electrons.
ii) Lone Pair / Non-Bonding Pair Electrons:
Those electrons which doesn't take part in bonding and are not shared between atoms. In given structure the lone pair of electrons are found only on nitrogen atoms (single lone pair) and oxygen atoms (two lone pair of electrons) respectively.
The experimental control is the standard used as a comparison for the experimental groups.
For example, you may be trying to find out how different types of disinfectants affect bacterial growth. The control group would receive <em>no</em> disinfectant whereas the experimental groups would be the ones on which the disinfectants were tested.
Hope this makes sense!
Are you looking for true or false? This is true
D. A constant pressure calorimeter would be used because an increase in heat causes an increase in pressure.