A decrease in H^+ concentration will lead to a decrease of the H2CO3 concentration since more of it will now dissociate to the bicarbonate ion (equilibrium position shifts towards the right). This is because as equilibrium position shifts towards the right as the hydrogen ions are removed it decreases the concentration of the carbonic acid in the system as shown by the equation above.
The new trend will probably be the technology that's in that certain year. Like the trend in the modern days are all electronics or will have to do with electronics. Hope this helps! :) Pls mark me as the BRAINLIEST!!!