Which of the following could be used to describe the rate of a reaction?

change in time/change in concentration

change in mass/change in concentration

change in concentration/change in time

change in concentration/change in mass

Change in concentration / Change in time

Explanation:

Whenever the "rate" of something is being spoken about, "rate" always refers to a change in something divided by time.

If the rate of a reaction is increased, that means the reaction is going faster, and hence would take less time. So mathematically, if the rate is "something" divided by time, and time decreases, the overall fraction is going to be larger, meaning the rate is higher.

In a chemical reaction, there is always reactants and products. A lot of the time, the reactants are being converted to products, and during this process, the concentration of reactants decrease, while the concentration of the products increase. The only way that we can tell how fast the reaction is going, is by calculating the concentration of either the reactants or the products.

Hence, the rate of a reaction is the change in concentration / change in time.

answer; /// the amount of material dissolved in a measure of liquid(concentration) the above statement is (true); /// good luck

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.