Which law says that during any physical or chemical change, the matter is neither created nor destroyed. however, it may change from one form to another ?

The number of moles of KMnO₄ that will be needed to react with one mole of sulphite ion in acidic solution is

Boron has two stable isotopes, .  Calculate average atomic weight of boron in the periodic table.

The equation E= mc² is introduced by

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

Which law states that, when two elements combine to form two or more compounds, then the different masses of one element, which combine with a fixed mass of the other element, bear a simple whole number ratio with one another ?

A metal oxide has the formula Z₂ O₃ .  It can be reduced by hydrogen to give free metal and water.  0.1596g of the metal oxide requires 6 mg of hydrogen for complete reduction.  The atomic weight of the metal is

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

Assuming fully decomposed, the volume of CO₂ releases at STP on heating 9.85 g of BaCO₃ (atomic mass, Ba = 137) will be