I think it should be A, not 100% sure tho
"These" should be referring to Alkali Metals.
They include metals such as Lithium, Sodium, Potassium etc.
They're classified as Group I elements because they all have one outmost shell electrons. This is why these metals are so reactive because they only need to lose one electron in order to achieve the octet of electrons (or duplet for Lithium), which means complete outmost shell electrons (2 or the 1st shell, others are 8).
The reason why they're especially reactive to Halogens (Group VII) elements are that Halogens have 7 outmost shell electrons, which only needs one more electron in order to get to the octet of electrons. So, if an Alkali metal reacts with a Halogen, the metal would give one of their electrons to the Halogen, that way, both of the elements can have an octet of electrons (or duplet).
<span>Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0 and 100%.</span>
Answer:
Explanation:
. Chemical digestion is the biochemical process in which macromolecules in food are changed into smaller molecules that can be absorbed into body fluids and transported to cells throughout the body. Substances in food that must be chemically digested include carbohydrates, proteins, lipids, and nucleic acids.
2.A fat molecule, such as a triglyceride, consists of two main components—glycerol and fatty acids. Glycerol is an organic compound with three carbon atoms, five hydrogen atoms, and three hydroxyl (–OH) groups.
3. If it's in the table, it's an element! Atoms can join together - they form bonds together - to make MOLECULES. For example, two atoms of hydrogen hook together to form a molecule of hydrogen, H2 for short.
4. When atoms join together to form molecules, they are held together by chemical bonds. These bonds form as a result of the sharing or exchange of electrons between the atoms. It is only the electrons in the outermost shell that ever get involved in bonding.
A compound is a molecule made of atoms from different elements. There are two main types of chemical bonds that hold atoms together: covalent and ionic/electrovalent bonds. Atoms that share electrons in a chemical bond have covalent bonds. An oxygen molecule (O2) is a good example of a molecule with a covalent bond.
5.Beginning with energy sources obtained from their environment in the form of sunlight and organic food molecules, eukaryotic cells make energy-rich molecules like ATP and NADH via energy pathways including photosynthesis, glycolysis, the citric acid cycle, and oxidative phosphorylation.
The first evidence of modern human traits, including increasing brain size and dependence on material culture shows up in Homo habilis. Even though they are species<span> of genus </span>Homo, they are not similar to people nowadays at all. <span>In </span>palaeoanthropology, these species were the first ones who left Africa and started to move and spread along Eurasia, which is one the main facts and characteristics of Homo habilis.
