EASY
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Which of the following is true about empirical formula and molecular formula?

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Important Questions on Some Basic Concepts of Chemistry

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)?
EASY
An organic compound contains 80% (by wt.) carbon and remaining percentage of hydrogen. The right option for the empirical formula of this compound is: [Atomic wt. of C is 12 and of H is 1]
MEDIUM

Compound A contains 8.7% Hydrogen, 74% Carbon and 17.3% Nitrogen. The molecular formula of the compound is, Given : Atomic masses of C,H and N are 12,1 and 14 amu respectively.

The molar mass of the compound A is 162 g mol-1.

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)
EASY
An organic compound contains 24% carbon, 4% hydrogen and remaining chlorine. Its empirical formula is
EASY
If Avogadro number NA , is changed from 6.022×1023 mol-1 to 6.022×1020 mol-1 , this would change:
MEDIUM
An organic compound contains 60%C; 4.48%H and 35.5% O. Its empirical formula 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
The empirical formula and molecular mass of a compound are CH2O and 180 g respectively. The molecular formula of the compound will be
MEDIUM
In a compound C, H and N are present in 9:1:3.5 by weight. If molecular weight of compound is 108, the molecular formula of compound is
MEDIUM
A mixture of gases contains H2 and O2 gases in the ratio of 1:4 (w/w). What is the molar ratio of the two gases in the mixture?
EASY
1.25 g of a metal (M) reacts with oxygen completely to produce 1.68 g of metal oxide. The empirical formula of the metal oxide is [Molar mass of M and O are 69.7 g mol-1 and 16.0 g mol-1 , respectively]
EASY
Suppose the elements X and Y combine to form two compounds XY2 and X3Y2. When 0.1 mole of XY2 weighs 10 g and 0.05 mole of X3Y2 weighs 9 g, the atomic weights of X and Y are
MEDIUM
An unknown chlorohydrocarbon has 3.55 % of chlorine. If each molecule of the hydrocarbon has one chlorine atom only; chlorine atoms present in 1 g of chlorohydrocarbon are :(Atomic wt. of Cl=35.5 u; Avogadro constant =6.023×1023 mol1)
EASY
The volume of oxygen at STP required to burn 2.4 g of carbon completely is:
EASY
A pure compound contains 2.4 g of C,1.2×1023 atoms of H,0.2 moles of oxygen atoms. Its empirical formula is
HARD
The ratio of mass percent of C and H of an organic compound CXHYOZ is 6 : 1. If one molecule of the above compound CXHYOZ contains half as much oxygen as required to burn one molecule of compound CXHY completely to CO2 and H2O. The empirical formula of the compound CXHYOZ is
EASY
A compound has the following composition by weight; Na=18.60%, S=25.80%, H=4.02% and O=51.58% Assuming that all the hydrogen atoms in the compound are part of water of crystallization, the correct molecular formula of the compound is