External factors that significantly impact a firm's pricing decisions are as follows:

1. Market Structures: In a perfectly competitive market, firms are price takers, meaning prices are dictated by supply and demand. In contrast, firms have more freedom to set prices in a monopolistic or oligopolistic market.
2. Demand Elasticity: If demand for a product is elastic, which means it is sensitive to price changes, a price increase could lead to a significant drop in the quantity demanded. Conversely, firms can raise prices without severely impacting sales volume if demand is inelastic.
3. Economic Conditions: In a strong economy, consumers may be willing to pay higher prices, allowing firms to charge more. In contrast, consumers become more price-sensitive during economic downturns, often forcing firms to lower prices or offer discounts.
4. Government Policies, such as regulation, price controls, taxes, tariffs, and subsidies, also impact price decisions.
5. Social Preferences: Changes in social trends and consumer preferences can affect pricing. For example, a growing preference for sustainable products might allow firms to charge a premium for eco-friendly offerings.

In summary, external factors play a critical role in pricing decisions. Firms must constantly monitor and adapt to these factors to optimize their pricing strategies.