Answer:
An ionic bond is formed between a metal and a non-metal. Covalent bonding is a form of chemical bonding between two non metallic atoms which is characterized by the sharing of pairs of electrons between atoms and other covalent bonds.
Explanation:
There are two types of atomic bonds - ionic bonds and covalent bonds. They differ in their structure and properties. Covalent bonds consist of pairs of electrons shared by two atoms, and bind the atoms in a fixed orientation. Relatively high energies are required to break them (50 - 200 kcal/mol). Whether two atoms can form a covalent bond depends upon their electronegativity i.e. the power of an atom in a molecule to attract electrons to itself. If two atoms differ considerably in their electronegativity - as sodium and chloride do - then one of the atoms will lose its electron to the other atom. This results in a positively charged ion (cation) and negatively charged ion (anion). The bond between these two ions is called an ionic bond.
They undergo internal fertilization and they have wet moist skin.
Answer:
This disorder is caused by a recessive allele, its inheritance is sex-linked.
Explanation:
The disorder affects boys born to unaffected parents, this means that at least one of them has to be a carrier of the allele which causes the disease. So, if the allele was dominant, it would express in parents and sons. But, in this case, only is expressed in sons, so it can´t be dominant. Moreover, this condition has a sex-linked inheritance because it is always seen in boys and never in girls. This happens due to boys only have an X chromosome, so if they inherit the recessive allele of the disease, they will express it. On the other hand, girls have two X chromosomes, so if they inherit one copy of the recessive allele, they will be carriers and they won't be affected.
This disorder is never seen in females because they need to have two copies of the recessive allele. However, to have double copy, they should inherit one copy from their mothers and one copy of their fathers, but boys with the allele are affected and they die in early teens without having progeny. Therefore, a girl can't have a "carrier-father", so they will never have two copies to express the disorder.
The answer is C because it’s something that can be caused by speciation, not can cause it
