Haemoglobin contains 0.33% of iron by weight.  The molecular weight of haemoglobin is approximately 67200.  The number of iron atoms (atomic weight of Fe is 56) present in one molecule of haemoglobin are

Law of constant composition was proposed by

In the final answer of the expression
the number of significant figures is

What volume of oxygen gas (O₂) measured at 0^o C and 1 atom is needed to burn completely 1 L of propane gas (C₃H₈) measured under the same conditions ?

How many moles of lead (II) chloride will be formed from a reaction between 6.5 g of PbO and 3.2 g of HCI ?

Which law says that when two elements combine separately with a definite mass of a third element, then the ratio of their masses in which they do so is either the same or some whole number multiple of the ratio in which they combine with each other ?

Specific volume of cylindrical virus particle is , whose radius and length are  respectively.  If , find molecular weight of virus.

Volume occupied by one molecule of water (density = 1 g cm^-3 ) is

The number of significant figures for the three numbers 161 cm, 0.161 cm, 0.0161 cm are

Law of constant composition was verified experimentally by