NEET Practice Questions (MCQs) with Answers & Solutions

(A). Physical and chemical adsoptions respond differently to a rise in temperature because

       chemical adsorption requires some activation energy. So, at low temperatures, it is very small

       but increases with a rise in temperature. At higher temperatures, it starts decreasing because

       the adsorbate molecules gain more kinetic energy and are able to leave the surface of the

       adsorbent. While in physical adsorption decreases with a rise in temperature.

(A). Catalyst in general, in the form of finely divided powder because finer is the particle of a solid,

       greater is its surface area. Larger surface leads to the greater adsorption of the reacting

       molecules on the surface. As a result, the reaction rate increases.

(C) It  is a fact.

(b) Alumino-thermic process is commonly used for those metals  which have very high m.pt. and are to be extracted from their oxides and their reduction with carbon is not satisfactory.

(D) 

Wrought Iron is the purest form of iron. It contains 0.12 to 0.25% carbon and so it is the purest form of iron.

(b) Calcination is a process in which the ore is heated strongly in the absence of air.

(a) Metals having high polarising power (Z_eff) exist in ore with anions having high polarisibility

Ag, Cu, Pb $\to$Sulphide ores (Ag₂S, CuFeS₂, Pbs)

Sn $\to$ Oxide ore (SnO₂)

Mg $\to$Sea water and dolomite  (CaCO₃, MgCO₃)

Al $\to$Oxide ore (Al₂O₃.2H₂O)

(b) Sulphur occurs in native state while iodine, phosphorus and magnesium are found in combined state.