Water is a pure substance. which of the following is true about water? a a chemical change is requirec to seperate the elemnts present in it b a physical change requirec to seperate the elemnts present in it c it is amde of two compounds, each witha different set of atoms d it is made up of an ekement and a compoumd.

A) a chemical change is required to seperate the elemnts present in it

Explanation:

Water is a compound, since it is the result of combining atoms: hydrogen and oxigen . In fact, the chemical formula of water is .

On the other hand, chemically in a compound the atoms must be combined in a fixed ratio by mass. In the case of the water molecule, the ratio is 2:1 (For each oxigen atom there are two hydrogen atoms).

So, if we want to separate the atoms that make up the water molecule, it only will be possible by a chemical change and not by a physical one.

Hence the correct option is A.

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.

a