The purchasing power of the Naira will fall when there is inflation. Inflation happens when the general price level of goods and services in an economy increases over time, making each unit of currency, such as the Naira, worth less in terms of what it can buy. For instance, if the price of a bag of rice increases from 10,000 Naira to 15,000 Naira, the Naira's purchasing power will have decreased, as it can now buy less than it could before.
Retrenching workers, changing the colour of the Naira, cutting all salaries and wages, or overvaluing the Naira do not necessarily lead to a fall in its purchasing power. However, if any of these factors contributes to inflation, it could ultimately lead to a decrease in the Naira's purchasing power.