Recent questions tagged some-basic-concepts-in-chemistry

A silicon (atomic weight=28) chip used in an integrated circuit of a microcomputer has a mass of 5.68 mg. How many silicon (Si) atoms are present in this chip.

asked Oct 25, 2013 by sreemathi.v

1 answer

In the first world war ,$1.1\times 10^8$kg of position gas were fired on the allied forces.If the gas is assumed to be phosgene,how many molecules of the gas correspond to the amount fired on allied forces.

asked Oct 25, 2013 by sreemathi.v

1 answer

$\large\frac{2}{3}$ of the atoms in water molecule are hydrogen .What % weight of a water molecule is the weight of 2 hydrogen atoms:

asked Oct 25, 2013 by sreemathi.v

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16g $SO_x$ occupies 5.6 litres at STP. Assuming the nature of the gas to be ideal, the value of $x$ is

asked Oct 25, 2013 by sreemathi.v

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Chlorophyll,a green coloring matter contains 2.68% mg.The number of atoms of mg present 1g chlorophyll are

asked Oct 24, 2013 by sreemathi.v

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4.4g of $CO_2$ and $2.24$ litre of $H_2$ at STP are mixed in a container.The total number of molecules present in the container will be

asked Oct 24, 2013 by sreemathi.v

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224 ml of triatomic gas weights 1g at 173k and 1atm .The mass of one atom of this gas is

asked Oct 24, 2013 by sreemathi.v

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Weight of oxygen in $Fe_2O_3$ and FeO in the simple ratio for the same amount of Fe is

asked Oct 24, 2013 by sreemathi.v

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Two elements $X$ and $Y$ have atomic mass 75 and 16 respectively.They combine to give a compound having 75.8%X.The formula is

asked Oct 24, 2013 by sreemathi.v

1 answer

Two oxides of a metal contain 50% and 40% of metal M respectively.If the formula of first oxide is MO,+ve formula of $2^{nd}$ oxide will be

asked Oct 24, 2013 by sreemathi.v

1 answer

An organic compound containing C and it has 92.3% carbon .Its empirical formula is :

asked Oct 24, 2013 by sreemathi.v

2 answers

A compound has an empirical formula $C_2H_4O$.An independent analysis gave a value of 132.16 for its molecular mass.What is the correct molecular formula ?

asked Oct 24, 2013 by sreemathi.v

1 answer

An organic compound contains 49.30% carbon,6.84% hydrogen and its vapour density is 73.Molecular formula of compound is

asked Oct 24, 2013 by sreemathi.v

1 answer

A compound on analysis,was found to have the following composition :(i) Na=14.31% (ii) S=9.97% (iii) O=69.50% (iv) H=6.22%.Calculate the molecular formula of the compound assuming that whole of hydrogen in the compound is present as water of crystallization .Molecular mass of the compound is 322.

asked Oct 24, 2013 by sreemathi.v

1 answer

A carbon compound containing only carbon and oxygen has an approximate molecular mass of 290.On analysis,it is found to contain 50% by mass of each element .What is the molecular formula of the compound?

asked Oct 24, 2013 by sreemathi.v

1 answer

A compound of carbon ,hydrogen and nitrogen contains these elements in the ratio 9 : 1 : 3.5.Calculate the empirical formula.If its molecular mass is 108,what is the molecular formula ?

asked Oct 24, 2013 by sreemathi.v

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A compound contains 34.8% Oxygen,52.2% Carbon and 13.0% hydrogen .What is the empirical formula mass of the compound ?

asked Oct 24, 2013 by sreemathi.v

1 answer

Calculate the empirical formula for a compound that contains 26.6% potassium,35.4% chromium and 38.1% oxygen.(Given :K=39.1,Cr=52,O=16)

asked Oct 24, 2013 by sreemathi.v

1 answer

The atomic composition of the entire universe is approximately given in the table below

asked Oct 23, 2013 by sreemathi.v

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A gas mixture contains 50% helium and 50% methane by volume .What is the percentage by mass of methane in the mixture

asked Oct 23, 2013 by sreemathi.v

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On analysis of an impure sample of sodium chloride,the percentage of chloride was found to be 45.5.What is the percentage of pure sodium chloride in the given sample ?

asked Oct 23, 2013 by sreemathi.v

1 answer

Hydrogen and oxygen are combined in the ratio 1 : 16 by mass in hydrogen peroxide.Calculate the percentage of hydrogen and oxygen in hydrogen peroxide.

asked Oct 23, 2013 by sreemathi.v

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Calculate the percentage of nitrogen present in the composition of calcium nitrate.

asked Oct 23, 2013 by sreemathi.v

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The oxide of an element contains 32.33 percent of the element and the vapor density of its chloride is 79.Calculate the atomic mass of the element.

asked Oct 23, 2013 by sreemathi.v

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One gram of a chloride was found to contain 0.835g of chlorine.Its vapor density is 85.Calculate its molecular formula

asked Oct 23, 2013 by sreemathi.v

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On dissolving 2.0g of metal in sulphuric acid 4.51g of the metal sulphate was formed.The specific heat of the metal is 0.057cal/g.What is the exact atomic mass of the metal?

asked Oct 23, 2013 by sreemathi.v

1 answer

A chloride of an element contains 49.5% chlorine.The specific heat of the element is $0.056$.Calcuate the equivalent mass,valency.

asked Oct 23, 2013 by sreemathi.v

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The equivalent weight of a metal is double than that of oxygen .How many times is the weight of its oxide greater than the weight of metal?

asked Oct 23, 2013 by sreemathi.v

1 answer

The percentage of an element $m$ is 53 in its oxide of molecular formula $M_2O_3$.Its atomic mass is about

asked Oct 23, 2013 by sreemathi.v

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A metal m of equivalent mass E forms an oxide of molecular formula $M_xO_y$ .The atomic mass of the metal is given by the correct equation.

asked Oct 23, 2013 by sreemathi.v

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How many years it would take to spend one Avogadro's number of rupees at a rate of 10lakh of rupees in one second

asked Oct 23, 2013 by sreemathi.v

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The electric charge on the electron is $1.602\times 10^{-19}$ coulomb.How much charge is present on 0.1 mole of $Cu^{2+}$ ions?

asked Oct 23, 2013 by sreemathi.v

1 answer

How many electrons are present in 1.6g of methane?

asked Oct 23, 2013 by sreemathi.v

1 answer