At a given temperature and pressure, a gas X diffuses twice as fast as gas Y. It follows that

The number of molecules of helium gas contained in 11.5g of the gas is

The constituents of Alnico are Aluminium, Nickel and 

Silver and Gold are metals found as free uncombined elements in the earth's crust, which makes them to be referred to as

In the extraction of Aluminium, the silica impurity is removed by