DAT Question of the Day

Correct Answer: D. average kinetic energy quadruples.

The temperature (in Kelvins) of a gas is directly proportional to the average kinetic energy of the gas. Therefore, if the temperature is quadrupled, so to is the average kinetic energy of the gas.

Subscribe below to get the DAT Question of the Day delivered straight to your inbox every morning.

Correct Answer: D. it increases, then becomes constant.

A pressure cooker fixes the atmospheric pressure to be higher than normal. In order for a liquid to boil, the vapor pressure inside of the container must be at least equal to the atmospheric pressure. For higher atmospheric pressures, like in a pressure cooker, the vapor pressure must also increase. Therefore, it takes longer for the vapor pressure of the gas to accumulate, leaving the liquid to become hotter and hotter. Once the boiling point is reached, the liquid is hotter than normal, cooking the food faster. Once the vapor pressure equals the environmental pressure of the pressure cooker, it remains constant. At this point the liquid is boiling and the vapor pressure of the liquid is equal to the atmospheric pressure of the pressure cooker. In this case, the only answer option that aligns correctly to what occurs in a pressure cooker is [D].

Subscribe below to get the DAT Question of the Day delivered straight to your inbox every morning.

Correct Answer: C. A pointer on a meter or surface of a liquid in a buret or pipette is not observed from directly straight on.

All options are common laboratory errors, but Parallax Error may occur when a pointer on a meter or surface of a liquid in a buret or pipette is not observed from directly straight on. If they are observed from above or below then the liquid surface or pointer will not be seen to line up with the scale.

Subscribe below to get the DAT Question of the Day delivered straight to your inbox every morning.

Correct Answer: A. High entropy, exothermic reactions with a low activation energy.

TNT explosions are very fast reactions (the lower the activation energy the less a reaction is impeded) involving the production of enormous quantities of heat (exothermic) and gaseous products (the production of hot gases from a solid explosive dramatically increases the disorder of the system, thus high entropy).

Subscribe below to get the DAT Question of the Day delivered straight to your inbox every morning.

Correct Answer: E. molecules absorb heat from the environment

When a liquid evaporates, it must have enough energy to break the intermolecular forces holding its particles together. To gain enough energy to do this, energy in the form of heat is absorbed from the surrounding environment. This is an endothermic process. If heat is absorbed from the environment, then the environment is left feeling cool as the liquid molecules begin to break their bonds/attractions and evaporate. It is true that in a solid the molecules remain in fixed locations and vibrate in place and liquid molecules slide across one another, however these do not explain the phenomenon of evaporative cooling.

Subscribe below to get the DAT Question of the Day delivered straight to your inbox every morning.

Correct Answer: C. Decreasing the OH- concentration in the solvent.

We see from the equation that the solubility is negatively affected by solvent content of OH. The more there is in the solvent, the less solubility the calcium hydroxide is. Thus, we can deduce that decreasing the OH concentration in the solvent will increase solubility.

Subscribe below to receive the DAT Question of the Day delivered straight to your inbox every morning.

Correct Answer: C. 0.333 g/mL

Density is calculated by dividing the grams of a substance by the volume it displaces, in either mL or L. In this case the density would be calculated as: 7.000g / 21.0mL = 0.333 g/mL

Note: The correct answer must have 3 significant digits because the 21.0 mL number used in the calculation had 3 significant digits. The rule for multiplying and dividing significant digits is the answer must have the same number of significant digits as the number with the least amount of significant digits.

Subscribe below to get the DAT Question of the Day delivered straight to your inbox every morning.

Correct Answer: A. NaI

This is a limiting reagent question. Only one of the reactants can “limit” the amount of CaI2 produced, therefore answer options [C] and [D] are eliminated. Even though the compounds are aqueous, dissolved in water, water is not written in the equation and therefore should not have an effect on the amount of product produced, thus eliminating answer option [E].
Next, we setup two equations to see the amount of CaI2 both reactants can make. The reactant that makes the SMALLEST amount of CaI2 is our limiting reagent.

NaI produces less mols of our product, so it must be the limiting reagent.

Subscribe below to get the DAT Question of the Day delivered straight to your inbox every morning.

Correct Answer: B. both have 8 protons

¹⁸O and O^-2 are both forms of oxygen. The former is an isotope and the latter is an ion. They do not have the same number of neutrons, as an isotope has a different number of neutrons. Likewise the ion does not have the same number of electrons as the isotope because the ion has gained 2 electrons from its neutral form. The only thing in common between an isotope and an ion is the number of protons. The number of protons within the nucleus of an element does not change.

Subscribe below to receive the DAT Question of the Day delivered straight to your inbox every morning.

Correct Answer: A. NO3^–

The base is a proton acceptor, and would therefore add a hydrogen to its chemical formula. Between the two compounds provided, NH4⁺ would behave as the acid, releasing hydrogen to get back to a zero charge and NO3^– would behave as the base accepting the hydrogen to return to its neutral state of HNO3.

Subscribe below to get the DAT Question of the Day delivered straight to your inbox every morning.