Why do reactants require relatively high-energy collisions to form products?

a. so that the orientation is correct for bond breaking to occur.
b. so that there are more frequent collisions.
c. reactants need to gain energy to break bonds and to form new ones.
d. no right answer

The correct option is C. Reactants need to gain energy to break bonds and to form new ones.

Explanation:

The Collision Theory explains the fact that for a chemical reaction to occur, the reactants must collide with one another with a force which breaks the bonds in the reactants, so that new bonds can be formed among the reactants. If molecules do not collide with a certain force, the chemical reaction won't occur. The energy with which the molecules collide is termed as the activation energy. The more the concentration of reactants, the more are the chances of collisions and the more will be the activation energy.

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.

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.