The  number of gram molecules of oxygen in  molecules is


Correct option is

5 g molecules


1 mol of CO = 1 g atom of O

or  molecules of 




A sample of hard water contains 20 mg of Ca2+ ions per litre. How manymilliequivalents of Na2CO3 would be required to soften 1 litre of the sample?


A plant virus is found to consist of uniform cylindrical particles of 150 Å in diameter and 5000 Å long. The specific volume of the virus is 0.75 cm3/ g. If the virus is considered to be a sample particle, find its molecular weight.


The formula weight of an acid is 82.0 in a titration 100 cm3 of a solution of this acid containing 39.0 g of the acid per litre were completelyneutralised by 95.0 cm3 of aqueous NaOH containing 40 .0 g of NaOHper litre. What is the basicity of the acid?


An analysis of a pyrex glass showed 12.9% B2O3, 2.2% Al2O3, 3.8% Na2O, 0.4% K2O and remaining is SiO2. What is the ratio of Si to B atoms in the glass?


One litre of a gas is at a pressure of 10–6 mm of Hg at 25oC. How many molecules are present in the vessel?


27 g of Al (at mass = 27) will react with oxygen equal to


2.76 g of silver carbonate (at mass of Ag = 108) on being heated strongly yields a residue weighing 


If 0.5 mol of BaCl2 is mixed with 0.2 mol of Na3PO4, the maximum number of moles of Ba3(PO4)2 that can be formed is


If 1021 molecules are removed from 200 mg of CO2, then the number of moles of CO2 left are


The molecular weight of O2 and SO2 are 32 and 64 respectively. If onelitre of O2 at 15oC and 750 mm contains N molecules, the number of molecules in two litres of SO2 under the same conditions of temperature and pressure will be