Rates of chemical reactions vary. which of the following can affect the rate of reaction among atoms or molecules?

D. All of these

Explanation:

Reaction rate is a measure of speed of a chemical reaction.

The following factors control reaction rates:

1. Nature of the reactants

2. Concentration of the reactants or pressure if gaseous.

3. Temperature

4. Presence of catalyst

5. Sunlight

The reaction rate is directly proportional to the concentration of the reactants. For gaseous systems, the pressure is directly proportional to the concentration and so pressure can be used in place of concentration.

Temperature change has a considerable effect on reaction rates since temperature is directly proportional to the average kinetic energy of reacting particles. Generally, reaction rate varies as temperature directly. For every 10°C rise in temperature above room temperature, it has been found that reaction rates becomes double or triple.

When temperature of a reacting system increases:

I. The kinetic energy of each of the reacting particles inceases

II. The frequency of ordinary colliosions and effective collisions per unit time increases.

III. Many of the reacting particles would require energy greater than or equal to the activation energy of the reaction.

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).