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(A): Pyrolusite is an ore of manganese. ...

(A): Pyrolusite is an ore of manganese.
(R) : Formula of pyrolusite is `Mn_(3)O_(4)`.

A

Both A & R are true, R is the correct explanation of A

B

Both A & R are true, R is not correct explanation of A

C

A is true, R is false

D

A is false, R is true

Text Solution

Verified by Experts

The correct Answer is:
C
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Pyrolusite is the main ore of manganese in which it is present as Its Mn content is determined by reducing it under acidic condition to Mn^(2+) with the help of oxalate (C_(2)O_(4)^(2-)) ion which in turn gets oxidized to CO_(2) The analytical determination is carried out by adding a known excess volume of (C_(2)O_(4)^(2-)) solution to a suspension of the pyrolusite and digesting the mixture on a hot water bath until all the MnO_(2) has been reduced. The excess unreacted oxalate solution is then titrated with standardized KMnO_(4) solution. Thereby Mn content of ore can be calculated. KMnO_(4) solution is also standardized under acidic condition against oxalate ion wherein MnO_(4)^(-) ion is reduced to Mn^(2+) and (C_(2)O_(4)^(2-)) ion is oxidized to CO_(2) Q If a student prepared a standard solution of Na_(2)C_(2)O_(4) by dissolving 3.2 g of dry anhydrous salt into distilled water and making the solution upto 500 mL. The Normality of oxalate solution is

Pyrolusite is the main ore of manganese in which it is present as Its Mn content is determined by reducing it under acidic condition to Mn^(2+) with the help of oxalate (C_(2)O_(4)^(2-)) ion which in turn gets oxidized to CO_(2) The analytical determination is carried out by adding a known excess volume of (C_(2)O_(4)^(2-)) solution to a suspension of the pyrolusite and digesting the mixture on a hot water bath until all the MnO_(2) has been reduced. The excess unreacted oxalate solution is then titrated with standardized KMnO_(4) solution. Thereby Mn content of ore can be calculated. KMnO_(4) solution is also standardized under acidic condition against oxalate ion wherein MnO_(4)^(-) ion is reduced to Mn^(2+) and (C_(2)O_(4)^(2-)) ion is oxidized to CO_(2) Q An alternative method for this analysis may be the replacement of oxalate with Fe^(2+) But this is less frequently used because it requires some special care otherwise we get low analytical results. The probable reaction responsible for this fact is :

MnO_(2) on ignition converts into Mn_(3)O_(4) . A sample of pyrolusite having 75% MnO_(2) , 20% inert impurities and rest water is ignited in air to constant mass. What is the percentage of Mn in the ignited sample ?

MnO_(2) is the most important oxide of manganese , MnO_(2) occurs natually as the black coloured mineral pyrolusite. It is an oxidising agent, and decomposes to Mn_(3)O_(4) on heating to 530^(@) C. It is used in the preparation of potassium permanaganate and in the productioon of Cl_(2) gas. Over half million tonnes per year of MnO_(2) is used in dry batteries. Q. When MnO_(2) is fused with KOH in the presence of air, the product formed is:

MnO_(2) is the most important oxide of manganese , MnO_(2) occurs natually as the black coloured mineral pyrolusite. It is an oxidising agent, and decomposes to Mn_(3)O_(4) on heating to 530^(@) C. It is used in the preparation of potassium permanaganate and in the productioon of Cl_(2) gas. Over half million tonnes per year of MnO_(2) is used in dry batteries. Q. MnO_(2) dissolves in concentrated HCl to form:

MnO_(2) is the most important oxide of manganese , MnO_(2) occurs natually as the black coloured mineral pyrolusite. It is an oxidising agent, and decomposes to Mn_(3)O_(4) on heating to 530^(@) C. It is used in the preparation of potassium permanaganate and in the productioon of Cl_(2) gas. Over half million tonnes per year of MnO_(2) is used in dry batteries. Q. In the laboratory, MnO_(2) is made by:

MnO_(2) is the most important oxide of manganese , MnO_(2) occurs natually as the black coloured mineral pyrolusite. It is an oxidising agent, and decomposes to Mn_(3)O_(4) on heating to 530^(@) C. It is used in the preparation of potassium permanaganate and in the productioon of Cl_(2) gas. Over half million tonnes per year of MnO_(2) is used in dry batteries. Q. In the laboratory, MnO_(2) is made by:

MnO_(2) is the most important oxide of manganese , MnO_(2) occurs natually as the black coloured mineral pyrolusite. It is an oxidising agent, and decomposes to Mn_(3)O_(4) on heating to 530^(@) C. It is used in the preparation of potassium permanaganate and in the productioon of Cl_(2) gas. Over half million tonnes per year of MnO_(2) is used in dry batteries. Q. In which of the following species, the colour is due to charge transfer? (I) [Mn(OH)_(4)]^(2-) (II) MnO_(4)^(2-) (III) MnO_(4) (IV) KMnO_(4)

The common name of the ore of iron - whose chemical formula is Fe_(3)O_(4)

Igniting MnO_(2) in air converts it quantitatively to Mn_(3)O_(4) . A sample of pyrolusite is of the following composition: MnO_(2) = 80% , SiO_(2) and other inert constituents = 15%, and rest bearing H_(2) O . The sample is ignited to constant weight. What is the percent of Mn in the ingnited sample?