Which is NOT an element that must be present for a fire to occur?a. heat
c. hydrogen
b. fuel
d. oxygen

Answer: mouth

Explanation:

The food digestion process in the human or animal body starts in the mouth. The mouth consists of teeth which helps in crushing and grinding of food. The mouth secretes saliva which provides lubrication to the food items. It helps in mixing process of the food so that it can be easily swallowed inside the gut and could enter into the digestive tract.

Answer:

Some elements are abbreviated with more than two letters such as the Ununtrium (Uut), Ununpentium (Uup), Ununseptum (Uus) and Ununoctio (Uuo).

Explanation:

Some elements have intuitive symbology, such as Chlorine (Cl), among others, which are represented by the first letters that make up the name. However, there are others who receive symbols that do not remember the name of the element, such as Lead (Pb). Regardless of the similarity between the names and the symbol of the elements, most of them have the symbol composed of one or two letters, except for the elements Ununtrium (Uut), Ununpentium (Uup), Ununseptum (Uus) and Ununoctio (Uuo).

1. Answer is d. all of the above.

Climate can be defined as the data collection of weather conditions of a long period of time in a certain area. The weather conditions that affect to the climate are temperature, precipitation, atmospheric pressure, wind and so on. Any changes in weather can change the global climate.

2. Answer is c. ozone.

Trees release oxygen and water vapor into the atmosphere but not ozone. The oxygen gas is released by trees as the by-product of photosynthesis. This is the natural way of production of oxygen gas. Water vapor can be released due to the transpiration of trees.

1. The correct answer is option D. all of the above.

Global climate change will bring changes in temperature such as heat waves, droughts, volcanic eruption, deforestation, extinction of species due to large shift in temperatures, changes in precipitation such as  heavy snowfall, ocean acidification, and ozone depletion.  

2. The correct answer is option C, ozone.  

Ozone is not released by trees into the atmosphere. Plants have chlorophyll and in the presence of sunlight plants uses sunlight and carbon dioxide to form glucose and oxygen.

6CO₂ + 6H₂O  ->  C₆H₁₂O₆ + 6O₂

During transpiration plants exhale water vapor through the stomata, tiny pores that are found on the surface of the leaves.

Thus trees never release ozone into the atmosphere.

Final answer:

To determine unpaired electrons, look at the valence electrons in an ion's molecule, accounting for extra or absent electrons due to the ion's charge. For instance, O2- and F2+ have one unpaired electron, but N22- is not a valid ion, and O22- electrons are all paired.

Explanation:

To determine if a molecular ion will have one or more unpaired electrons, we need to look at the number of valence electrons in the molecule and take into account any extra or absent electrons due to the charge of the ion.

For example, O2- has 12 + 1 = 13 valence electrons (6 from each oxygen atom and 1 extra due to the negative charge). It requires 14 for all the electrons to be paired (2 in each oxygen's inner shell and 4 bonds or lone pairs in the outer shell), thus there is one unpaired electron in O2-.

However, in F2+, there are only 13 electrons because one electron is lost due to the positive charge. Like oxygen, fluorine also prefers to have 7 electrons in its outer shell, so there are also unpaired electrons in F2+.

N22- doesn’t exist because nitrogen normally forms triple bond and doesn’t need or want to take extra electrons, so this molecular ion is not valid.

O22- has 14 + 2 = 16 valence electrons and this total number of valence electrons is an even number, which indicates all the electrons are paired.

Learn more about Unpaired Electrons here:

brainly.com/question/29656941

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