When two atoms of Florine combines, they share an electron pair to complete it's octet. This result is formation of single bond between two fluorine atoms. This process is exothermic in nature, and hence, heat is liberated during the process of bond formation. <span />
1) D = 13.6 g / mL
2)ethyl alcohol weighs 158g
3)ρ
_copper = 8.9 g 
Explanation:
1)
D = m / V
=306.0 g / 22.5 mL
D= 13.6 g / mL
2)
density = mass / volume
mass = density × volume
=0.789g /ml × 200.0 ml
M=158g
Ethyl alcohol weighs 158g
3)
ρ (density) = Mass / Volume
ρ
_copper = 1896 g / 8.4cm × 5.5cm × 4.6cm
= 1896g / 212.5 
ρ
_copper=8.9 g 
Basically all of the elements found in Group I of the periodic table also have this property. The ability to easily give up a single valence electron.
External
Stimuli are anything that causes arousal or enables an object to respond or react.
There are many different kinds of stimuli for which is different for every organism, for example, water, light and carbon dioxide are three stimuli and materials needed for photosynthesis in plants to manifest.
<span>In humans, we have nutrients or food, oxygen and water for us to survive. These are stimuli, eyes need light as a stimuli for it see and function. Nasal receptors needs smell as stimuli caused by molecular reactions of an object as a stimuli. And others. </span>