Which of the following is a secondary pollutant?

$1.$ $\mathrm{CO}$

$2.$ ${\mathrm{CO}}_2$

$3.$ ${\mathrm{SO}}_2$

$4.$ ${\mathrm{O}}_3$

Match the items given in Column I with those in Column II and select the correct option given below: 

Which one of the following statements is not valid for aerosols ?

1. They are harmful to human health
2. They alter rainfall and monsoon patterns
3. They cause increased agricultural productivity
4. They have negative impact on agricultural land

A lake which is rich in organic waste may result in
(1) increased population of aquatic organisms due to minerals

(2) drying of the lake due to algal bloom

(3) increased population of fish due to lots of nutrients

(4) mortality of fish due to lack of oxygen

The highest DDT concentration in aquatic food chain shall occur in 
(1) phytoplankton

(2) seagull

(3) crab

(4) eel

Depletion of which gas in the atmosphere can lead to an increased incidence of skin cancers
(1) ozone

(2) ammonia 

(3) methane

(4) nitrous oxide

Joint Forest Management Concept was introduced in India during
(1) 1970s

(2) 1980s

(3) 1990s

(4) 1960s

A river with an inflow of domestic sewage rich in organic waste may result in

1. increased population of aquatic food web organisms

2. an increased production of fish due to biodegradable nutrients

3. death of fish due to lack of oxygen

4. drying of the river very soon due to algal bloom