Determine the Empirical formulae of an oxide of iron which has 69.9% iron and 30.1% dioxygen by mass.

A hydrocarbon was found to contain approximately 75% carbon and 25% hydrogen by mass. Calculate the empirical formula of the hydrocarbon, assuming relative atomic masses of carbon and hydrogen as 12 and 1.

Urea forms an ideal solution in water. Determine the vapour pressure of an aqueous solution containing 10% by mass of urea at 40^@C .[Vapour pressure of water at 40^@C = 55.3mm of Hg ]

Calculate the concentration of nitric acid in molarity in a sample which has a density, 1.41g/ml and contain 49% by mass of nitric acid

Define effciency of a heat engine .can you design an engine which has the 100% efficiency ?

In which mineral iron (II) iron (III) oxide occur?

A solid iron pole consists of a cylinder of height 220cm and base diameter 24 cm,which is surmounted by another cylinder of height 60cm and radius 8 cm.Find the mass of the pole,given that 1cm^3 of iron has approximately 8g mass.(use pi=3.14 ).

You are given circular discs of equal masses and thickness, but one is made of iron and the other of alminium. Which one will have large MI about the central axis?

Find the values of a and b for which the following system of linear equation has infinitely many solutions. 2x-(2a+5)y=5, (2b+1)x-9y=15