MEDIUM
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Insulin contains 3.4% sulphur. Calculate minimum molecular weight of insulin.

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Important Questions on Some Basic Concepts of Chemistry

EASY
1 g of an organic compound containing C and H, on complete combustion produced 3.04 g of CO2 and 1.53 g of H2O. Find the approximate percentage composition of C and H in the compound.
MEDIUM
Complex A has a composition of H12O6Cl3Cr. If the complex on treatment with conc. H2SO4 loses 13.5% of its original mass, the correct molecular formulas of A is:
[Given : atomic mass of Cr=52 amu and Cl=35 amu]
EASY
Calculate the percentage by weight of oxygen in a mole of water?
HARD
In Carius method of estimation of halogens, 250 mg of an organic compound gave 141 mg AgBr. What is the percentage of bromine in the compound (atomic mass of Ag=108 and atomic number of Br=80)?
HARD
A 1.85 g sample of an arsenic-containing pesticide was chemically converted to AsO43-  (atomic mass of As = 74.9) and titrated with Pb2+ to form Pb3 AsO42 . If 20 mL of 0.1 M Pb2+ is required to reach the equivalence point, the mass percentages of arsenic in the pesticide sample is closest to
EASY
In the crystalline solid MSO4·nII2O of molar mass 250 g mol-1, the percentage of anhydrous salt is 64 by weight. The value of n is
EASY
In an estimation of bromine by Carius method, 1.6g of an organic compound gave 1.88g of AgBr. The mass percentage of bromine in the compound is ..
(Atomic mass, Ag=108, Br=80 gmol-1
HARD

In a non-stoichiometric sample of cuprous sulphide, with the composition Cu1.8S, cupric ions are also present in the lattice. What mole percent of Cu2+ is present in the copper content of the crystal?

HARD
One mole of one of the sodium salts listed below, having carbon content close to 14.3% produces 1mole of carbon dioxide upon heating (Atomic masses: Na = 23, H = 1, C = 12, O = 16). The salt is
HARD
An organic compound contains C, H and S. The minimum molecular weight of the compound containing 8% Sulphur is
HARD
Complete combustion of 750 g of an organic compound provides 420 g of CO2 and 210 g of H2O. The percentage composition of carbon and hydrogen in organic compound is 15.3 and ______ respectively. (Round off to the Nearest Integer)
EASY

When 0.15 g of an organic compound was analyzed using Carius method for estimation of bromine, 0.2397 g of AgBr was obtained. The percentage of bromine in the organic compound is _________.(Nearest integer)

[Atomic mass : Silver =108, Bromine =80]

MEDIUM
A metal M (specific heat 0.16 ) forms a metal chloride with 65% chlorine present in it. The formula of the metal chloride will be
MEDIUM
Among the following nitrogen compounds, which one has lowest percentage of nitrogen?
MEDIUM

116 g of a substance upon dissociation reaction, yields 7.5 g of hydrogen, 60 g of oxygen and 48.5 g of carbon. Given that the atomic masses of H,O and C are 1,16 and 12, respectively. The data agrees with how many formulae of the following?

A. CH3COOH

B. HCHO

C. CH3OOCH3

D. CH3CHO

MEDIUM
A protein 'A' contains 0.30% of glycine (molecular weight 75). The minimum molar mass of the protein 'A' is____×103 g mol-1 [nearest integer]
EASY
The percentage composition of carbon by mole in methane is:
EASY
The percentage of nitrogen by mass in ammonium sulphate is closest to (atomic masses H = 1, N = 14, O = 16, S = 32)
MEDIUM
A sample of a hydrate of barium chloride weighing 61 g was heated until all the water of hydration is removed. The dried sample weighed 52 g. The formula of the hydrated salt is: (atomic mass, Ba = 137 amu, Cl = 35.5 amu)