What is true when a reaction has reached equilibrium?

the concentration of products and reactants is constant.

the reaction has stopped.

the concentration of the products is changing.

the concentration of the reactants is changing.

The concentration of the products and reactants is constant.

Explanation:

Once the reversible reaction that proceeds forward and backward simultaneously has reached it's state of chemical equlibrium, the concentration of products and reactants become constant.

This means that the rate at which the reactants react to form products becomes equal to the rate at which products react to form the reactants again. At this point there will be no further change in the concentration of reactants and products with time. In chemical equilibrium the concentration of a reactant or a product is expressed in moles per cubic decimeter ( mol / dm^3.

im not exactly sure but i think its b!

the best answer is d because the strong cohesion is caused by the ability of water molecules to undergo hydrogen bonding.

a is incorrect because when water solidifies, it becomes   ice, which expands and occupies a bigger volume for the same mass of water in its liquid state.

b is incorrect because water has high surface tension. besides bonding to itself it hydrogen bonds to other molecules at the top decreasing possibility for breaking of attractive forces.

c is incorrect because the water molecule has oxygen which is highly electronegative and so pulls the electron pair towards itself creating a dipole moment, making the molecule polar.

e is incorrect because water has strong adhesion, ability to stick to other molecules such as glass because of this molecules having stronger hydrogen bonding than water.