A) consider a two-dimensional crystal made up of spherical atoms that are packedtogether as tightly as possible in a plane. show that the unit cell may be drawn as a hexagon with an atom in the center and atoms at each of the six corners. how many atoms are there per cell? (5 pts.) show that it is also possible to draw the unit cell as a parallelogram that has an empty center and atoms at each of its corners. how many atoms does this cell contain? how many unit cells of type (b) are contained within a single hexagonal cell of type ( pts.) consider a two-dimensional crystal that has a hexagonal unit cell with an empty center and atoms located at the corners of the hexagon. draw the atom positions generated by several neighboring cells. show that the unit cell used in part (b) is not a correct unit cell for this structure.(5 pts.) draw a proper set of lattice vectors for the structure in (c). indicate the basis vectors that are needed to complete the description of the structure. given your choice of lattice vectors, what atom group is repeated at each lattice point?

Darla claims that the first periodic table developed by mendeleev was not completely accurate, so it is not useful at all. harmony argues that it establish the periodic table we use today, making it more credible. who is correct and why? darla is correct, because a model that has any mistakes should be thrown out. darla is correct, because a good model would not need to change. harmony is correct, because mendeleev’s model had all of the information correct in the first version. harmony is correct, because mendeleev’s model made predictions that came true.

Brainliesttt me asap! the below reaction can be categorized as more than one type of reaction. which reactions are these, and what are the types of reactions?

Astudent made a graph plotting the progress of a reaction over time. the student forgot to label the y-axis of the graph. a graph is shown with two graph lines. one graph line starts at a higher position on the y axis and slopes downwards towards the right. the other graph line starts at a lower position on the y axis and slopes upwards towards the right. the two graph lines stop short of intersecting each other and continue as separate lines which gradually become straight and parallel to the x axis. a vertical line is shown at a point where the two graph lines finally became parallel to the x axis. this vertical line is labeled equilibrium. the title on the x axis is time and an arrow pointing towards the right is shown above time. the title on the y axis is left blank. what best explains the label that the student should use on the y-axis? amount, because as the amount of product decreases, the amount of reactant increases over time. reaction rate, because forward and backward reaction become equal at equilibrium. amount, because the amounts of reactants and products become constant after equilibrium is reached. reaction rate, as the rate of forward reaction increases and rate of backward reaction decreases over time.