In which of the following, do both pairs have the correct combination?

1.	Gaseous nutrient cycle Sedimentary nutrient cycle	Carbon and nitrogen Sulphur and phosphorous
2.	Gaseous nutrient cycle Sedimentary nutrient cycle	Carbon and sulphur Nitrogen and phosphorus
3.	Gaseous nutrient cycle Sedimentary nutrient cycle	Nitrogen and sulphur Carbon and phosphorous
4.	Gaseous nutrient cycle Sedimentary nutrient cycle	Sulphur and phosphorous Carbon and nitrogen

During ecological succession:

The vertical distribution of different species occupying different levels in a biotic community is known as:

Secondary succession takes place on/in:

The mass of living material at a tropic level at a particular time is called:

In an ecosystem, the rate of production of organic matter during photosynthesis is termed as:

1. net primary productivity

2. gross primary productivity

3. secondary productivity

4. net productivity

Match the following and select the correct option: 

1. A-(i), B-(ii), C-(iii), D-(iv)

2. A-(i), B-(ii), C-(iii), D-(iv)

3. A-(iii), B-(ii), C-(iv), D-(i)

4. A-(ii), B-(i), C-(iv), D-(iii)

Given below is a simplified model of phosphorus cycling in a terrestrial ecosystem with four blanks (A-D). Identify the blanks. 

If 20 J of energy is trapped at the producer level, then how much energy will be available to peacocks as food in the following chain? 
Plant → mice → snake → peacock