Question

List any 2 human activities that lead to an increase in the carbondioxide content in the air

Answer 1

Deforestation and burning fossil fuels

Answer 2

Burning of wood and charcoal for heating, cooking etc.
Deforestation that reduces the green plants and tree population , consequently lessening the utilization of atmospheric CO2.  
Burning of fossil fuels such as petrol, diesel and coal in various activities like transportation and industrial processes.