Covalent bonds are formed when valence electrons are between a. shared; ions b. shared; atoms c. transferred; ions d. transferred; atoms

Option B is correct.

B.shared; atoms

A covalent bond, also called a molecular bond, is a chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs, and the stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding.

B. shared; atoms

Explanation:

Covalent bond is formed by sharing of electrons between two atoms. In this way full outer shell is achieved by both the atoms. Since there is no gain or loss of electrons, no ions are formed in the process.

It is usually formed between the atoms of similar electronegativity. It can be of many types like sigma bond, pi bond etc. If a pair of electrons is shared, it's a single bond. If two pairs are shared, it's a double bond and if three pairs are shared, it's a triple bond.

common management practices in dairy and poultry farming are: (i) proper shelter facilities and their regular cleaning. (ii) some basic hygienic conditions such as clean water, nutritious food, etc. (iii) animals are kept in spacious, airy, and ventilated place.

answer: decrease

a limiting factor is the one which decrease the abundance, distribution and causes extinction of the population of species in a ecosystem. here, predators including hawks, owls and snakes are the limiting factor for the population of mexican free tailed bat.   although bats are nocturnal animals as they forge for food at night these predators also may remain active during night which can decrease the population of the mexican free-tailed bats. also, these bats eat only one type of insects that are moths. the food can also be a limiting factor as all 400 members are dependent upon same type of food needs that are moths. the decrease in the moth population can cause decrease in population size of the mexican free-tailed bats.

therefore, the scenarios will most likely to decrease the population size of the mexican free-tailed bats.