Common salt obtained from sea-water contains `8.775% Na Cl` by mass. The number of formula units of `NaCl` present in `25 g` of this salt is :

Common salt is obtained from sea water by

A complex of iron contains 45.6% iron by mass. Calculate the number of iron atoms present in 15.0 g of this complex.

Chlorophyll, the green colouring matter of plants contains 2.68% of magnesium by mass. Calculate the number of magnesium atoms present in 2.5 g of chlorophyll.

Calculate the number of atoms present in one drop of water having mass 1.8 g .

Common salt can be separated from sea water by the process of filtration. Do you agree? Give reason.

The following data were obtained from experiments to find the molecular formula of benzocaine, a local anaesthetic. (i) 3.54 g of it gave 8.49 g of CO_2 and 2.14 g of H_2O on complete combustion. (ii) 2.35 g of it was found to contain 0.199 g of nitrogen. (iii) The molecular mass of benzocaine was found to be 165 amu. Find the molecular formula of benzocaine.

The common salt was obtained from two different sources. In one sample, the percentage of chlorine was found to be 60.75 %. In the second sample, 3.888 g of chlorine were present in 6.4 g of the salt. Show that these data are in accordance to the law of constant proportion.

13.4 g of a sample of unstable hydrated salt Na_(2)SO_(4).XH_(2)O was found to contains 6.3 g of H_(2) O . The number of molecular of water of crystalistion is

Calculate mass of sodium which contains same number of atoms as are present in 4 g of calcium (Atomic weight Na = 23 , atomic weight Ca = 40 )

A solution contains 40 g of common salt in 320 g of water. Calculate the concentration in terms of mass of mass percentage of the solution.