D. Drop in barometric pressure, warm ocean water, humid air. The low pressure brings in a cool air mass causing collision of two different masses.
My father rode out a typhoon near Okinawa WWII, onboard the battleship USS Missouri BB-63.
Violent pitching, alarms going off for approaching capsize pitch. The captain came on loudspeaker “ don’t worry men, land is near... about a mile straight down”.
Potassium chloride reacts with ammonium nitrate to give ammonium chloride and potassium nitrate.
This is a type of double displacement reaction. The balanced chemical equation can be represented as,

Total ionic equation for this reaction will be,

There is no apparent reaction as this reaction is not accompanied by the formation of a gas or a solid precipitate. We cannot observe any visual reaction as there is not net reaction taking place. All the ions remain as spectator ions.
Answer: E. It decreases the value of Eact.
Explanation:
Activation energy is the extra energy that must be supplied to reactants in order to cross the energy barrier and thus convert to products.
A catalyst is a substance which increases the rate of a reaction by taking the reaction through a different path which involves lower activation energy and thus more molecules can cross the energy barrier and more molecules convert to products.
The catalyst itself does not take part in the chemical reaction and is regenerated as such at the end.