Shallow Gas

Recently, in which of the following country, fourth largest reservoir of shallow gas in the world has been discovered?

Rare Earth Elements

With reference to Rare Earth Elements(REE), consider the following statements:

Rare Earth Elements (REE) is the collective name for 19 chemically similar metallic elements (the lanthanides, Scandium and Yttrium) that occur in a wide range of REE bearing minerals and are mined collectively.
The principal economic sources of rare earths are the minerals bastnasite, monazite, and loparite and the lateritic ion-adsorption clays.

Choose the correct answer from the codes given below:

Explanation :

The Rare Earth Elements (REE) are a set of seventeen metallic elements. These include the fifteen lanthanides on the periodic table plus scandium and yttrium.
15 REE are- lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).
The principal economic sources of rare earths are the minerals bastnasite, monazite, and loparite and the lateritic ion-adsorption clays.
Although these elements are referred to as rare they are not particularly rare in the earth’s crust. Cesium is the 25th most abundant crustal element and lutetium, the scarcest REE, is about the 60th most abundant.

REEs are categorized as being either light or heavy:

Light REEs (lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium and scandium) are produced in global abundance and are in surplus supply
Heavy REEs (terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and yttrium) are produced mainly in China and are in limited supply.

Their unique magnetic, luminescent, and electrochemical properties make them essential to such products as smartphones, electric cars, camera lenses, X-ray scanners, wind turbines, and computer hard drives.
REE are essential raw materials for a wide range of applications, including metallurgy (metal refining and metal alloying), catalysts in the automotive and the petro-chemical industry, colouring of glass/ceramics, phosphors (LEDs, compact fluorescent lamps, flat panel displays), lasers, rechargeable solid state batteries (Ni-MH), fibre optics and others.
Additionally, REE are vital elements in emerging technologies such as solid state fuel cells, superconductors, magnetic cooling, hydrogen storage and high performance permanent magnets.