According to Avogadro's law, each mole of a compound contains . Use dimensional analysis to find the number of molecules in .

Use dimensional analysis:

Avogadro's number tells us how many molecules of gas are in one mole of the container. We are essentially doing a unit conversion from "number of molecules" to moles -

The definition of molality is moles of solute in 1 kg of the solvent, whereas molarity is the number of moles of solute per 1 L of solutioin. Since 1 mol of CaCl2 is added to 1 L of water, this means that the volume of the final solution is greater than 1 L. Thus, molality is the more accurate concentration determinant, since the solution is probably close to 1 L. 

Molarity, molality, and normality are the three principle ways to measure concentration. Molarity is a measure of moles of solute per liter of solution. Molality is a measure of moles of solute per kilogram of solvent. Normality expressly relates to acids and bases, and is the measure of moles of solute divided by the number of hydrogen equivalents per mole, all divided by liters of solution. Normality is also referred to as "equivalents (of acid) per liter."

Molarity is defined as moles of solute divided into liters of solution. We can set up the equation as follows:

Set the left side of the equation over  and solve as a proportion.

Cross multiply.

Remember molarity is defined as moles of solute per liter of solution.

Substiute.

Liters cancel out.

Solve for the number of moles. This gives us  of solute in a ,  solution of .

 is the dimensional breakdown for the commonly used unit , or molarity, for concentration. 

While the other units might be seen in chemistry, they are used for other topics. 

Millimeters of mercury (mmHg) and atmospheres (atm) are seen in regards to pressure. 

 is the dimensional breakdown for density. And  is the dimensional breakdown for a Newton, also written as N. This is associated with force. 

Scientific notation is used to simplify exceptionally complex numbers and to quickly present the number of significant figures in a given value. The value is converted to an exponent form using base ten, such that only a single-digit term with any given number of decimal places is used to represent the significant figures of the given value. Non-significant zeroes can be omitted from the leading term, and represented only in the base ten exponent.

The given number has four significant figures (3123), so there will be four digits multiplied by the base ten term.

To generate the single-digit leading term the decimal must be placed after the first 3. Then count the digits to the right of the decimal (123). Our ten will be raised to the power of three.

Our final answer is 

Scientific notation is used to simplify exceptionally complex numbers and to quickly present the number of significant figures in a given value. The value is converted to an exponent form using base ten, such that only a single-digit term with any given number of decimal places is used to represent the significant figures of the given value. Non-significant zeroes can be omitted from the leading term, and represented only in the base ten exponent.

The given number has three significant figures (321), so there will be three digits multiplied by the base ten term.

To generate the single-digit leading term the decimal must be placed after the 3 (3.21). Then count the digits to the left of the decimal (moving from right to left, these are 3, 0, 0). Our ten will be raised to the power of negative three because there are three digits to the left of the final decimal placement.

Our final answer is .

Scientific notation is used to simplify exceptionally complex numbers and to quickly present the number of significant figures in a given value. The value is converted to an exponent form using base ten, such that only a single-digit term with any given number of decimal places is used to represent the significant figures of the given value. Non-significant zeroes can be omitted from the leading term, and represented only in the base ten exponent.

The given number has five significant figures (100.43), so there will be five digits multiplied by the base ten term.

To generate the single-digit leading term the decimal must be placed after the 1 (1.0043). Then count the digits to the right of the decimal to determine the change in decimal placement (the decimal moves past the two zeroes). Our ten will be raised to the power of two because there are two digits to the right of the final decimal placement.

Our final answer is