Ncert Solutions Chemistry Class 12th
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6 months agoContributor-Level 10
Cryolite (Na3AlF6) has two roles in the metallurgy of aluminium:
(i) It lowers the melting point of the mixture to about
(ii) It increases the electrical conductivity of the
New answer posted
6 months agoContributor-Level 10
Copper matte contains Cu2S and FeS. When a blast of hot air is passed through molten matte took in a silica lined convertor, FeS present in matte is oxidized to FeO which combines with Silica (SiO2) to form FeSiO3, slag.
When the whole of iron has been removed as slag, some of the Cu2S undergoes oxidation to form Cu2O which then reacts with more Cu2O to form copper metal.
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6 months agoContributor-Level 10
The naturally occurring substances in the form of which metals occur in the earth's crust along with impurities are called as minerals. The mineral from which the metal can be extracted conveniently and profitably is called as an ore. Thus, all ores are minerals but all minerals are not ores. For example, aluminium occurs in earth's crust in the form of bauxite and clay. Out of these two minerals, aluminium can be conveniently and economically extracted from the bauxite. Therefore, bauxite is the ore of aluminium. Similarly, Zinc can be obtained from blende (ZnS), calamine (ZnCO3), Zincite (ZnO) etc.
Thus these minerals are called ores
New answer posted
6 months agoContributor-Level 10
The iron obtained from blast furnaces is known as pig iron. It contains around 4% carbon and many impurities such as S, P, Si, Mn in smaller amounts.
Cast iron is obtained by melting pig iron and coke using a hot air blast. It contains a lower amount of carbon (3%) than pig iron, cast iron is extremely hard and brittle.
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6 months agoNew answer posted
6 months agoContributor-Level 10
To separate alumina from silica in bauxite ore associated with silica, firstly, the powdered ore is digested with a concentrated NaOH solution at a temperature of 473 – 523K and 35 – 36 bar pressure. This results in the leaching out of alumina (Al2O3) as sodium aluminate and silica (SiO2) as sodium silicate leaving the impurities behind.
Al2O3 (s) + 2NaOH (aq) + 3H2O (l) → 2 Na [Al (OH)4] (aq)
SiO2 + 2NaOH (aq)→ Na2SiO3 (aq) + H2O (l)
After this, CO2 gas is passed through the resultant solution to neutralize the alumina present in the solution, this results in the precipitation of hydrated samples of alumina. To include precipitat
New answer posted
6 months agoContributor-Level 10
Nickel is refined by Mond's process. In this process, nickel is heated in the presence of carbon monoxide to form nickel tetracarbonyl, which is a volatile complex.
New answer posted
6 months agoContributor-Level 10
7.52
Oxygen is smaller in size as compared to sulphur. Due to its smaller size, it can effectively form p – p bonds and form O2 [O = O] molecule. Also, the intermolecular forces in oxygen are weak van there Wall's, which cause it to exist as a gas.
On the other hand, sulphur does not form M2 molecule but exists as a puckered structure held together by strong covalent bonds. Hence, it is a solid.
New answer posted
6 months agoContributor-Level 10
The components selected for the stationary phase should have different solubility's in the phase, only then it is selected as the stationary phase. Hence, different components have different rates of movement through the stationary phase; as a result, can be separated from each other.
New answer posted
6 months agoContributor-Level 10
7.51
The elements of group 16 are collectively called chalcogens.
[i]. Elements of group 16 have six valence electrons each. The general electronic configuration of these elements is ns2 np4, where n varies from 2 to 6.
[ii]. Oxidation state: As these elements have six valence electrons [ns2np4], they should display an oxidation state of -2. However, only oxygen predominantly shows the oxidation state of -2 owing to its high Electronegativity. It also exhibits the oxidation state of -1 [H2O2], zero [O2], and +2 [OF2].
However, the stability of the -2 oxidation state decreases on moving down a group due to a decrease in the El
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