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The percentage of Se in peroxidase anhydrous enzyme is 0.5% by weight (atomic weight =78.4). Then minimum molecular weight of peroxidase anhydrous enzyme is

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Important Questions on Some Basic Concepts of Chemistry

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The mass of carbon anode consumed (giving only carbon dioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is:
(Atomic mass: Al=27)
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An element X has the following isotopic composition:

X200: 90%X199: 8.0%X202: 2.0%

The weighted average atomic mass of the naturally occurring element X is closest to

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How many moles of Lead (II) Chloride will be formed from a reaction between 6.5g of PbO and 3.2g of HCl

Given the atomic mass of Pb=207.2

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An organic compound contains carbon, hydrogen and oxygen. Its chemical analysis gave C=38.71% and H2=9.67 %. The empirical formula of the compound would be:
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What volume of oxygen gas O2 measured at 0°C and 1 atm is needed to burn completely 1 L of  propane gas C3H8 measured under the same conditions?
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Volume occupied by one molecule of water (density =1g cm-3 ) is:
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10 g of hydrogen and 64 g of oxygen were filled in a steel vessel and exploded. Amount of water produced in this reaction will be ? 
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25.3 g of sodium carbonate, Na2CO3 is dissolved in enough water to make 250 mL of solution. If sodium carbonate dissociates completely, the molar concentration of sodium ion, Na+and carbonate ions, CO32- are respectively (Molar mass of Na2CO3=106 g mol-1 ):