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Chemistry Questions and Answers (Q&A)

The correct answer to this question is C, phosphorus pentachloride. The P stands for Phosphorus, while the Cl represents chloride. The 5 means that there are 5 Cl atoms bonded to the Phosphorus atom, which represents the prefix Pentain the Pentachloride. The naming conventions for a molecular compound is based on the number of atoms.

Phosphorus Pentachloride is a colorless, water-sensitive, and moisture-sensitive solid, meaning it is water soluble. It was first created by an English chemist named Humphry Davy in 1808. His analysis was inaccurate, and thus a French chemist, Pierre Louis Dulong, revised Davy's analysis providing the first accurate analysis in 1816.

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The correct answer to this question is B, Iron(II) oxide. Iron(II) oxide is also know as ferrous oxide following the older system of naming conventons. It is an inorganic compound. Since Oxygen has an oxidation number of -2, Iron must have a +2 charge.

The roman numerals are used to indicate the charge on the cation when elements form more than one type of ionic compound. Thus, Fe2+ and O2- creates FeO and becomes Iron(II) Oxide. Iron(II) oxide is a black-colored powder. Many confuse it for rust, which is not true. It does, however, make up about 9% of Earth's mantle.

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The correct answer to this question is B. Composition stoichiometry refers to the atomic makeup of a molecule, the quantitative relationships among elements in compounds, and is the study of the mass relationships among reactants and products in a chemical reaction.

Composition stoichiometry can also be used to figure out the number of atoms that are in a compound or collection of molecules, as well as the masses of each. Composition stoichiometry was defined by German chemist Jeremias Benjamin Richter in 1792, when he discovered that the ratio by weight of the compounds consumed in a chemical reaction was always the same.

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To create a balanced equation when aluminium reacts with copper (II) sulphate, provide the correct coefficient for each compound. Be sure to count all atoms on each side of the chemical equation.
Of all the options above only option listed above, only option B is correct.
2AL + 3CuSO4 ( AL2(SO4)3 +3Cu.
On both sides of the equation we have:
Aluminium atoms
3 copper atoms
and a balanced sulphuric acid.

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The correct answer to this question is D; the empirical formula for a compound that is 43.6% phosphorus and 56.4% oxygen is P2O5. In the formula, the P stands for phosphorus and the O standards for oxygen, so there are 2 phosphorus (P) atoms and 5 oxygen (O) atoms in the compound.

The atomic mass of phosphorus (P) is 30.974 u and the atomic mass of oxygen (O) is 15.999 u. Therefore, the total weight of phosphorus in the compound is 61.948, and the total weight of oxygen in the compound is 79.995. The total weight of the compound is 141.943, so phosphorus is 43.6% of the compound and oxygen is 56.4%.

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The correct answer to this question is B, 43.2 g. The mass of the glucose in one mole is calculated and then compared. First, one must identify that there are : 12 H = 1.0079g x 12 =12.0948 g , 6 C = 12.011g x 6 = 72.066 g , and 6 O = 15.9994g x 6 = 95.9964 g .

Once we have these figures, we must add and find the mass of glucose in one mole. One mole glucose is 180.157 g. Knowing that we can find our answer using the equation, 0.240 mol glucose x (180.157 g glucose / 1 mol glucose), which equals 43.238 g glucose

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The correct answer to this question is A. The nucleus of the atom was discovered by Ernest Rutherford in the year of 1911. Born in New Zealand, Rutherford is a British physicist considered as the father of nuclear physics. He discovered the atomic nucleus based on the Geiger–Marsden gold foil experiment from 1909, where Rutherford directed Hans Geiger and Ernest Marsden which used a thin gold foil to discover the nuclear nature of atoms.

Rutherford's interpertation of the data allowed him to create Rutherford modle of the atom, concluding that every atom possesses a nucleus holding its positive charge and majority of its mass, orbited around low-mass electrons.

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The correct answer to this question is C. Density is a physical property due the ratio between a substance's mass and volume. A physical property is something that does not change the chemical composition of the substance being observed. When you measure density, you place your subject on the scale to calculate mass, and then calculate volume by measuring the lengths and dividing the two.

Alternatively, you can measure density by using the displacement of liquid method, the volume of the liquid after the subject/object is immersed in the liquid, minus its original volume will give you substance's volume, then measuring mass on the scale. Since no chemical reaction is involved in measuring the density of a substance, it is considered a physical property.

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The opposition that a substance offers due to the flow of electric current is called resistance. Resistivity is the electrical opposition per unit length, area, or volume of an element. Resistance contrasts with conductance, which is a measure of the ease with which electrical current flows through a substance.

The resistance of a substance is precisely proportional to the length of the material. The less conductivity, the higher the resistance there is. When electrons are propelled through a metal that has significant resistance, heat is generated, which is why the burner on your electric stove gets hot. A large amount of electricity is being pushed through a metal that has a high resistance, and it gets hot.

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The answer to this is letter C. You need to solve in order to get this answer. There are only two steps so you do not have to make a lot of effort to solve. The first step is to divide your grams and then divide by molar mass. This will become 118.082 grams divided by 39.1 grams. The answer will be 3.02 moles.

You are not done yet because you still have to do the second step. Change the moles to atoms by multiplying it with the Avogadros number. The equation will be 3.02 x 6. 02 x 10^23. You will get the answer for letter C which is 1.818 x 10^24 atoms. You can use the same formula when you are solving similar problems.

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