He valence of selenium depends on which compound it is in. Selenium is very similar to sulfur. It may have a valence of 6; example selenium hexafluoride SeF6, selenium trioxide SeO3
<span>4; example selenium tetrafluoride SeF4, selenium dioxide SeO2 </span>
<span>2; example selenium difluoride SeF2, selenium dichloride SeCl2 </span>
<span>and -2; example hydrogen selenide H2Se</span>
Comets are balls of ice and dust in orbit around the Sun. The orbits of comets are different from those of planets - they are elliptical. A comet's orbit takes it very close to the Sun and then far away again.
Answer: IONIC EQUATION.
Explanation:
A chemical equation is defined as the form by which a chemical reaction is represented mathematically. These are written in the form of symbols and chemical formulas of reactants and products which are taking part in the chemical reaction. A chemical equation can be written in two forms, these include:
--> MOLECULAR EQUATION: in this type of equations, the compounds are written and represented in a molecular form. This is sometimes referred to as a balanced equation.
--> IONIC EQUATION: This is a type of chemical equation in which the electrolytes in aqueous solution are expressed as dissociated ions. A typical illustrated example is seen in the reaction between AgNO3(aq) and NaCl(aq) :
Ag+(aq) + NO3-(aq) + Na+(aq) + Cl-(aq) → AgCl(s) + Na+(aq) + NO3-(aq)
The (aq) written in the above equation signifies they are in aqueous solution.
The local environmental changes are having a global effect, and that is well documented and constantly witnessed. The reason why local environmental changes can have such a big impact is that the gasses move freely throughout all of the planet, they move horizontally with the winds, and they also move vertically higher into the atmosphere which is in constant movement.
This results in a situation where one area produces lot of pollution, but another area is feeling the effects because the air masses moved big portion of the polluters there.
A nice example are China and Mongolia. China is one of the two major polluters in the world, while Mongolia barely has any industry especially when considered its size and population. The air masses though are moving from the southeast towards northwest, thus big portion of the pollution in the eastern part of China goes into Mongolia. Because of this, despite not being a big polluter, Mongolia has one of the worst air qualities in the world.
Also, we can witness that the holes in the ozone layer are mostly around the poles, despite the sources of the chemicals that are damaging it are on totaly different locations.
Kinetic and potential energy
