Chemistry MCQs for NEET — Practice Questions with Answers

(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.

(b) Mond's process is used for the purification of Ni.

(c) This is Van-Arkel method for purification of Ti.

(d) Ni(CO)₄ $\stackrel{∆}{\to }$ Ni + 4CO

(b) For purification of Ni in Mond's process.

(b) The reaction involved in cyanide extraction process are:

Ag₂S +4NaCN $\to$2Na[Ag(CN)₂]+Na₂S

4Na₂S + 5[O₂] + 2H₂O $\to$2Na₂SO₄ + 4NaOH + 2S

2Na[Ag(CN)₂]+ZN $\to$Na₂[Zn(CN)₄]+2Ag$\downarrow$

(b) Both Ag and Au are extracted by complex formation method

(d)

    Mineral             Chemical composition
Malachite                   CuCO₃.Cu(OH)₂
Cassiterite                  SnO₂
Pyrolusite                   MnO₂
Magnetite                   Fe₃O₄

Thus, magnetite is a mineral of iron