5. what is the difference between covalent bonds and ionic bonds?
a - covalent bonds are formed between atoms to form molecules; ionic bonds are formed between atoms to form compounds.
b - covalent bonds involve the sharing of pairs between atoms; ionic bonds involve the sharing of single electrons between atoms.
c - covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the electrical attraction between atoms.
d - covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the sharing of protons between atoms.
8. an example of a van der waals interaction would occur is when
a - two polar covalent bonds react
b - an electron is lost from a hydrogen atom
c - electrons are not distrubuited in a symmetrical fashion in a molecule
d - overlapping occurs between hybrid orbitals
9. which of the following is responsible for the cohesive property of water?
a - hydrogen bonds between the oxygen atoms of two adjacent water molecules
b - covalent bonds between the hydrogen atoms of two adjacent water molecules
c - hydrogen bonds between the oxygen atom of one water molecule and a hydrogen atom of another water molecule
d - covalent bonds between the oxygen atom of one water molecule and a hydrogen atom of another water molecule
e - hydrogen bonds between water molecules and other types of molecules

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.

d concave shape of wave rock

explanation:

the concave shape of wave rock is a very good evidence that supports the evolution of earth due to chemical weathering. if we talk about structure of   wave rock, studies have estimated that it is around 2.7 billion years old. it also serves as the foundation of evidence that it was the place where australian continent began to form.

how the structure of wave rock was created?

studies suggest that structure of wave rock was created when the surrounded area was started to weather due to which deposition of material started on the part of land which now contains wave rock.

the structure of wave rock is considered to be one of the best-known landforms in australia. at the height of around 15 cm, there can be found flared slopes which formulate the margins of hyden rock. it is now assumed by geologists that wave rock was created by subsurface water-induced weathering and not by glaciers, waves or wind.

due to deposition of material over the period of long time, the wave rock became tougher and tougher due to weathering from surrounding terrain. this makes it a physical evidence that supports   the evolution of earth due to chemical weathering.

hope it !

colors do exist. the color of the sky is actually violet; humans percieve the color of the sky as blue.