The reaction of a salt, like , with an acid, like , is a double-replacement reaction. The products are a salt of the original acid (), and a second acid formed from the original salt (). Remember to keep the equation balanced.

The first step is writing, and then balancing, the chemical equation for this reaction.



From this, we are able to see that for every one mole of iron (III) nitrate that is produced, three moles of sodium bromide are produced (a 1 to 3 ratio).

The limiting reagent in this reaction is the acetyl chloride (because water is never the limiting reagent; there is always an excess of water). To solve this question, we need to convert the mass of acetyl chloride to moles. The molecular weight of acetyl chloride is:

The moles of acetyl chloride is:

The moles of hydrochloric acid produced is:

The molecular weight of  is equal to . The mass of  produced is:

The question states that the total amount of products produced is . This means that each product has  (because of 1:1 ratio). To solve this question, we need to check each answer choice to see which one matches the given information. Let’s start with the correct answer first.

Molecule A is sodium chloride and molecule B is potassium bromide. The molecular weight of sodium chloride is and the MW of potassium bromide is . The question states that we start with  of each molecule; therefore, the number of moles of each molecule is

moles of molecule A = 

moles of molecule B = 

Since it has the lower amount of moles, molecule B is the limiting reagent. We can now calculate the moles of products produced.

moles of product C = 

moles of product D = 

The calculated amounts matches with the information given in the question; therefore, molecule A is sodium chloride, molecule B is potassium bromide, and the limiting reagent is potassium bromide.

If we follow this procedure for the other answer choices we will notice that the results don’t match with the given information.

The first step is to determine the limiting reagent. To do this we need to first calculate the moles of reactants. The MW of hydrochloric acid is  and MW of cesium hydroxide is . The moles of each reactant is

Next step is to write out the balanced chemical reaction

The ratio of reactants is 1:1; therefore, since  has the smaller amount of moles it is the limiting reagent. This means that all of cesium hydroxide will be utilized in this reaction and the researcher won’t be able to salvage any cesium hydroxide. Note that there will be excess  left after completion of reaction.  of  will react with  of ; therefore, there will be a total of  of excess  .

Young's Modulus is equal to the stress over strain on an object. The stress on an object refers to the pressure that is put on an object, and can be given the below equation.

The strain on an object refers to the amount an object is deformed in the direction of the force. It can be given the below equation, where  is the change in length and  is the original length.

Combining these two equations we can determine Young's Modulus.

To find the right answer, we need to know two formulas:

The simplest way to compare these choices will be to convert them all to Kelvin.

This makes our answer .

In this question, you will have to use the given equation twice; once for melting point and once for boiling point. Let’s first convert the melting point to Fahrenheit. The question states that the melting point of water is . Plugging this into the equation gives:

The melting point of water is . Similarly, we convert the boiling point of water to Fahrenheit:

The boiling point is . The difference between boiling point and melting point in Fahrenheit is:

Kelvin is a temperature scale that is named after Lord Kelvin. Lord Kelvin, through his experiments, found that absolute zero  occurs at a temperature of . Later, scientists defined Kelvin as the fraction  of the temperature of water at its triple point (the point on a phase diagram at which water exists as a solid, a liquid, and a gas). This is because the temperature at the triple point of water, in Celsius, is . In Kelvin scale, the triple point of water occurs at .

The question states that the melting point of iron is . We can use the given equation to convert this to Celsius.

This means that the melting point of iron is . At this point you can choose the right answer because there is only one answer option that has ; however, let’s solve for Kelvin. The second equation you need to know is the conversion from Celsius to Kelvin:

The melting point of iron in Kelvin is: