NEET Practice Questions (MCQs) with Answers & Solutions

Mica is a group of minerals, the most important of which are muscotive ${\mathrm{H}}_2{\mathrm{KAl}}_3{\left({\mathrm{SiO}}_4\right)}_3$ and phlogopite ${\mathrm{H}}_2{\mathrm{KMg}}_3\mathrm{Al}{\left({\mathrm{SiO}}_4\right)}_3$ having sheet structure.

The mica group of sheet silicate (phyllosilicate) minerals includes several closely related materials having nearly perfect basal cleavage. All are monoclinic, with a tendency towards pseudohexagonal crystals, and are similar in chemical composition. The nearly perfect cleavage, which is the most prominent characteristic of mica, is explained by the hexagonalsheet-like arrangement of its atoms.

$\mathrm{Ge}$ possesses more tendency to show +4 oxidation state.

Silicon carbide is next to diamond in hardness.

Silicon carbide (SiC), also known as carborundum /kɑːrbəˈrÊŒndÉ™m/, is a semiconductor containing silicon and carbon.

use as an abrasive. Grains of silicon carbide can be bonded together by sintering to form very hard ceramics that are widely used in applications requiring high endurance, such as car brakes, car clutches and ceramic plates in bulletproof vests. Electronic applications of silicon carbide such as light-emitting diodes (LEDs) and detectors in early radios were first demonstrated around 1907. SiC is used in semiconductor electronics devices that operate at high temperatures or high voltages, or both. Large single crystals of silicon carbide can be grown by the Lely method and they can be cut into gems known as synthetic moissanite.

${\mathrm{Mg}}_2{\mathrm{C}}_3 + 4{\mathrm{H}}_2\mathrm{O} \stackrel{ }{\to } 2\mathrm{Mg}{\left(\mathrm{OH}\right)}_2+ {\mathrm{CH}}_3\mathrm{C}\equiv \mathrm{CH}$

$\mathrm{CO} + {\mathrm{Cl}}_2 \stackrel{ }{\to } {\mathrm{COCl}}_2 \left(\mathrm{Phosgene}\right)$

Chrome yellow is lead chromate.

Chrome yellow is lead(II) chromate (PbCrO₄). It occurs naturally as the mineral crocoite but the mineral ore was never used as a pigment for paint.

Chrome yellow had been commonly made by mixing solutions of lead nitrate and potassium chromate and filtering off the lead chromate precipitate.

Because the pigment tends to react with hydrogen sulfide and darken on exposure to air over time, forming lead sulfide, ^[2] and it contains the toxic heavy metal lead plus the toxic, carcinogenic chromate, it was replaced by another pigment, cadmium yellow.

It is a buff coloured crystalline compound.

PbO. Litharge is a secondary mineral which forms from the oxidation of galena ores. It forms as coatings and encrustations with internal tetragonal crystal structure. It is dimorphous with the orthorhombic form massicot. It forms soft (Mohs hardness of 2), red, greasy-appearing crusts with a very high specific gravity of 9.14–9.35. PbO may be prepared by heating lead metal in air at approximately 600 °C (lead melts at only 300 °C). At this temperature it is also the end product of oxidation of other lead oxides in air.^[4] This is often done with a set of bellows pumping air over molten lead and causing the oxidized product to slip or fall off the top into a receptacle, where it quickly solidifies in minute scale

It is also known as minium .

Lead(II,IV) oxide, also called red lead is the inorganic compound with the formula Pb3O4. ... Lead(II,IV) oxide is prepared by calcination of lead(II) oxide (PbO; also called litharge) in air at about

450-480 °C:

6 PbO + O2 → 2 Pb3O4.

uses

1. It is popular ingredient for the paint industry because of the rust blocking feature it has.

2. In addition, paint consisting of red lead oxide is used for protecting iron from getting rusted.

3. There is a range of applications it is put to use such as, anti-corrosive coatings, battery manufacturing, crystal glass, ceramics, mining, and crystal glasses.

$\mathrm{C}+4{\mathrm{HNO}}_3 \stackrel{ }{\to } {\mathrm{CO}}_2+4{\mathrm{NO}}_2+2{\mathrm{H}}_2\mathrm{O}$

$$\begin{gathered} {\mathrm{R}}_3\mathrm{SiCl} + \mathrm{HOH} \stackrel{ }{\to } {\mathrm{R}}_3\mathrm{SiOH} + \mathrm{HCl} \\ {\mathrm{R}}_3\mathrm{SiOH} + {\mathrm{HOSiR}}_3 \stackrel{ }{\to } {\mathrm{R}}_3\mathrm{Si}—\mathrm{O}—{\mathrm{SiR}}_3 \end{gathered}$$