Which of the following is true about catalysts?

catalysts increase the number of collisions that occur between reactants.
catalysts increase the activation energy by forming new reactants.
catalysts reduce the potential energy of the compounds that are produced.
catalysts reduce the energy needed for the reaction to take place.

The correct answer is that the catalysts enhances the collisions numbers that take place between the reactants.

Explanation:

A component that assists in elevating the rate of a chemical reaction without itself getting spent is known as a catalyst. A catalyst generally reduces the activation energy so that the molecules comprising low energy can take part in the process. As a consequence, there takes place more amount of collisions amongst the molecules. Thus, the rate of reaction will enhance because of which the production of products will become quicker. Thus, it can be concluded that the catalysts enhances the collisions taking place between the reactants.

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure  

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.