DAT Daily Questions

Ammonia (Kb = 1.8 x 10-5) is titrated with HBr. Which pH indicator should you use to signal the end point of the titration? thymol blue; pH=2-2.5 methyl yellow; pH=3-5.5 bromocresol purple; pH=6-8 cresol red; pH=8-9 alizarine yellow; pH=10.5-12

)methyl yellow; pH=3-5.5 (For the titration of a weak base with a strong acid, the equivalence point, or end point of the titration, will be a weak acid. An indicator with a pH range at the pH of the end point is needed. A weak acid has a low pH, but higher than that of a strong acid.)

In a soccer game, there are ten players on the field. How many different teams of six can be chosen?

10!/(10-6)!6! 10*9*8*7*6!/4!6! 10*9*8*7/4! 10*9*7/3 =210 possible combinations

Which of the following has a negative ∆Srxn? A. freezing B. sublimation C. vaporization D. fusion E. pressure decreasing

A. freezing phase changes going in the reverse direction (gas to liquid or liquid to solid) are associated with a decrease in the entropy of the system. Take freezing, for example: molecules of liquid water become more ordered by coming together to form solid ice. This increase in order is the same as a decrease in entropy, so answer choice [A] is correct.

A mouse is shocked with an extremely bright light. Afterwards, the mouse is fearful of entering bright areas of a room. Which of the following best describes this behavior? A. insight B. reflex C. habituation D. instinct E. sensitization

A. insight Insight is a form of associative learning. It involves learning in a new situation where no reinforcement is required. The mouse associates bright light with pain, making it fearful of new, bright, areas. [A] is the answer.

Identify each of the following compounds as aromatic, non-aromatic, or anti-aromatic. pentane ring (+C, 2 dbl bonds), pentane ring (-C, 2 dbl bonds), pentane ring (2dbl bonds)

Anti-aromatic; Aromatic; Non-aromatic

Which of the following has a non zero enthalpy of formation? A. Hg (l) B. Cl2 (l) C. N2 (g) D. H2 (g) E. C (graphite)

B. Cl2 (l) Cl2 is a gas at standard state (not a liquid), thus, will have a non zero enthalpy of formation.

All of the following are examples of associative learning EXCEPT one. Which one is the exception? A. spacial learning B. fixed action patterns C. observational learning D. sensitization E. habituation

B. fixed action patterns

x is a prime number and is a factor of 18. What is x? 1. x is a one-digit number 2. x is divisible by 2 A. statement (1) alone is sufficient, but statement (2) alone is not sufficient B. statement (2) alone is sufficient, but statement (1) alone is not sufficient C. both statements together are sufficient, but neither statement alone is sufficient D. each statement alone is sufficient E. statement (1) and (2) together are not sufficient

B. statement (2) alone is sufficient, but statement (1) alone is not sufficient We can begin by finding each of the factors of 18. They are 1,2,3,6,9, and 18. Of these, only 2 and 3 are prime numbers. Recall that a prime number is any whole integer that is divisible only by itself and 1. Statement (1) tells us that x is a one-digit number. Since both 2 and 3 are one-digit numbers, this statement does not help us; statement (1) alone is insufficient. Statement (2) tells us that x is divisible by 2. 2 is divisible by 2, but 3 is not. This means that x=2. Thus, statement (2) by itself is sufficient. Thus, [B] is the correct answer; Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

What is the area of the rectangle? One side is twice as long as the other The perimeter of the rectangle is 36 A. statement (1) alone is sufficient, but statement (2) alone is not sufficient B. statement (2) alone is sufficient, but statement (1) alone is not sufficient C. both statements together are sufficient, but neither statement alone is sufficient D. each statement alone is sufficient E. statement (1) and (2) together are not sufficient

C. both statements together are sufficient, but neither statement alone is sufficient

If the conjugate acid of a molecule has a pKa of 1.2, what would you expect the molecule to be? A. strongly acidic B. weakly acidic C. neutral D. weakly basic E. strongly basic

D. weakly basic

Which of the following could you add to increase the solubility of CaBr2? A. HCl B. HBr C. H2SO4 D. NaNO3 E. KOH

E. KOH

All of the following are a result of coevolution EXCEPT one. Which one is the EXCEPTION? A. camouflage B. aposematic coloration C. bayesian mimicry D. mullarian mimicry E. homoplasy

E. homoplasy

What is the value of x? x2 - 2x -15 (x - 5)(x + 3) = 0 A. statement (1) alone is sufficient, but statement (2) alone is not sufficient B. statement (2) alone is sufficient, but statement (1) alone is not sufficient C. both statements together are sufficient, but neither statement alone is sufficient D. each statement alone is sufficient E. statement (1) and (2) together are not sufficient

E. statement (1) and (2) together are not sufficient

What does PCC do?

PCC oxidizes primary alcohols to aldehydes

All of the following are characteristics of the desert terrestrial biome EXCEPT one. Which one is the EXCEPTION? cold nights very little rain hot days seasonal fires extreme weather fluctuation

seasonal fires