How many times have mass extinctions of species occurred since $3$ billion years ago to the present?

The colonisation of tropical........ by humans is said to have led to the extinction of more than $2000$ species of native birds.

The Amazon rain forest is being cut and cleared for cultivating which plant?

Which of the following are recently extinct subspecies of tiger?

Assertion: Tropical rain forests are disappearing fast from developing countries such as India.
Reason: No value is attached to these forests because these are poor in biodiversity.

Why do exotic species sometimes become invasive and start spreading rapidly?