State any three positive and any two negative effects of petroleum industry on the economy of Nigeria.

The petroleum industry is central to Nigeria's economy and has both positive and negative effects.

Positive effects (any three):

1. Source of government revenue: oil provides the largest share of government income through royalties, taxes and sales, financing budgets and development projects.
2. Foreign exchange earner: crude oil is Nigeria's main export, earning the bulk of the country's foreign exchange for imports and debt servicing.
3. Employment and income: the industry creates direct and indirect jobs (exploration, refining, transport, services), raising incomes and living standards.
4. Infrastructural and industrial growth: oil wealth has helped fund roads, power and by-products (petrol, kerosene, petrochemicals) that support other industries.

Negative effects (any two):

1. Environmental pollution: oil spillage and gas flaring destroy farmland, rivers and fishing, harming the health and livelihood of oil-producing communities.
2. Over-dependence on one product: heavy reliance on oil makes the economy vulnerable to falls in world oil prices and has led to neglect of agriculture and manufacturing.
3. Corruption and social unrest: struggles over oil revenue have encouraged corruption, militancy and conflict in the Niger Delta.