Explain what is meant by economic terms like market failure,  externalities,  welfare loss,  and allocative efficiency. Provide some real-life examples that can be explained using the above terms.
Market failure is a situation where the allocation of resources by a free market does not result in an efficient outcome. In other words, the market fails to allocate goods and services in a way that maximizes society's overall welfare. Market failures can arise due to a variety of reasons, such as incomplete information, externalities, public goods, and monopolies.

Externalities refer to the costs or benefits that are imposed on third parties who are not involved in the transaction. For example, a factory that pollutes the environment is imposing a negative externality on nearby residents who may suffer from health problems. In contrast, a person who gets vaccinated against a contagious disease generates a positive externality by reducing the spread of the disease to others.

Welfare loss refers to the reduction in economic well-being that occurs when resources are not allocated efficiently. Welfare loss can occur due to market failures, such as externalities, public goods, or imperfect competition. For example, if a monopolist sets a price higher than the marginal cost of production, consumers may be forced to pay more than they would in a competitive market, resulting in a welfare loss.

Allocative efficiency refers to the situation where resources are allocated in a way that maximizes social welfare. In other words, it occurs when the marginal social benefit of a good or service is equal to its marginal social cost. Allocative efficiency ensures that resources are allocated in a way that maximizes the overall well-being of society.

Real-life examples of these economic terms include:

Market failure: The financial crisis of 2008 was a result of a market failure. Banks and financial institutions engaged in risky lending practices, which led to the collapse of the housing market and a worldwide recession.

Externalities: Smoking imposes a negative externality on non-smokers who may suffer from health problems due to second-hand smoke. On the other hand, education generates a positive externality by increasing the overall productivity and well-being of society.

Welfare loss: A government policy that imposes a price floor on agricultural products may result in a surplus of goods that cannot be sold, leading to a welfare loss for both producers and consumers.

Allocative efficiency: The use of congestion pricing in urban areas can help to achieve allocative efficiency by ensuring that the price of using roads reflects the marginal social cost of congestion. This can encourage drivers to use public transportation or carpooling, reducing traffic congestion and improving overall social welfare.
When second hand smoke is an external input it isn’t a economic externality.
I’m sorry, but I think you are mistaken. Second hand smoke is an example of a negative externality, because it imposes a cost on non-smokers who are exposed to it. According to some studies, second hand smoke can cause various health problems, such as respiratory infections, asthma, cancer, and heart disease. These health problems can result in higher medical expenses and lower productivity for non-smokers. Therefore, second hand smoke reduces social welfare and causes a market failure.

Do you have any other questions about economic terms?
What are some other examples of health issues that are an economic externality?