Which of the following mixtures could not be separated by filtration? salty water muddy water orange juice with pulp in it dusty air

Option (a) is the correct answer.

Explanation:

Filtration is a technique or process in which solid that is suspended in a liquid is separated from the liquid.

For example, a muddy water can be filtered as particles of mud can be separated from the water.

Particles of salt being ionic in nature completely dissolve in water and it forms a homogeneous solution. Therefore, a mixture of salt water cannot be separated.

Thus, we can conclude that out of the given options salty water is the mixture which cannot be separated by filtration.

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)