Consider the following pairs with reference to sedimentary rocks and the process of their formation :  

Sedimentary Rock		Process of Formation
1.	Chere	Chemically formed
2.	Geyserite	Organically formed
3.	Shale	Mechanically formed

Which of the pairs given above is/are correctly matched ? 

Which of the following statements is/are correct ?

1. Oceanic trenches are very significant in the study of plate movements

2. Oceanic trenches are associated with active volcanoes and strong earthquakes

Select the answer using the code given below :  

Which of the following statements with reference to shadow zones in an event of an earthquake is/are correct ?

1. Zone between 105° and 145° from epicentre was identified as the shadow zone for both P-waves and S-waves

2. The shadow zone of P-waves is much larger than that of the S-waves

Select the answer using the code given below : 

Which one among the following volcanic island chains is NOT associated with mid-oceanic ridge ?