Achemical reaction has reached equilibrium when all products have been removed from the reaction mixture the catalyst has been used up the rate of the forward reaction equals the rate of the reverse reaction the concentrations of reactants and products are equal all reactants have been converted to products

A chemical reaction has reached equilibrium when the rate of the forward reaction equals the rate of the reverse reaction

Chemical reaction is the reaction of product formation from reactants

In industrial or laboratory processes, the reaction can be reversible

Generally this reaction occurs in closed room conditions

In a reaction will occur, initially there will be a decrease in the concentration of reactants and an increase in product concentration. The reaction speed value of the reactants is also getting smaller and smaller and the reaction speed value of the product is getting bigger and bigger. At one time, the reactant reaction speed will be the same as the reaction speed of the product so that equilibrium occurs, as if the reaction has stopped (no observable changes = macroscopic properties). But the reaction still occurs at the microscopic level (molecular)

Let's look at the answer choices

the product taken will cause the reaction to go in one direction towards the product, so that equilibrium will not occur

The catalyst serves to increase the rate of reaction because it decreases the activation energy, but the catalyst does not change because it remains in the reaction until the final stage of the reaction

The equilibrium reaction occurs if the reaction rate to the right (towards the product) is equal to the reaction rate to the left (towards the reactants) so v (rate)to the right = v(rate) to the left

At the beginning of the reaction, the reactant concentration will decrease and the concentration of the product will increase. The concentration of the product and reactants will remain different until the end of the reaction, but at a state of equilibrium the concentration of each substance is constant

In the equilibrium state, the reaction will be incomplete after some reactants react, because a product is formed which is simultaneously decomposed back into products

the rate of a reaction

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the rate of a reaction can be increased

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Endothermic and exothermic reactions

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the rate of a reaction can be increased2

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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.