Chemistry

Which type of change is different from the other four?

(A) Baking a potato
(B) Rusting of an iron nail
(C) Burning a piece of paper
(D) Melting an ice cube
(E) Ignition of propane
Chemistry

2019 U.S. National Chemistry Olympiad Local Section Exam Question 19

The specific heat capacity of iron is 0.461 J g–1 K–1 and that of titanium is 0.544 J g–1 K–1 . A sample consisting of a mixture of 10.0 g Fe and 10.0 g Ti at 100.0 ºC loses 200. J of heat to the environment. What is the final temperature of the sample?

(A) 89.9 ºC
(B) 80.1 ºC
(C) 60.2 ºC
(D) 39.8 ºC
Chemistry

2019 U.S. National Chemistry Olympiad Local Section Exam Question 18

One unit cell of a crystal containing elements X, Y, and Z is shown below. What is its formula?

(A) XYZ
(B) XYZ3
(C) XY4Z2
(D) XY8Z6
Chemistry

The study of matter is called

(A) Chemistry
(B) Biology
(C) Geology
(D) Physics
(E) Psychology
Chemistry

Which principal energy level has exactly four subshells?

(A) 1
(B) 2
(C) 3
(D) 4
(E) 5
Chemistry

2019 U.S. National Chemistry Olympiad Local Section Exam Question 17

A portion of the phase diagram of uranium hexafluoride (UF6) is shown below.

Which statements are correct?

I.  UF6 sublimes at atmospheric pressure.
II. At 80 ºC and 1.5 atm, only UF6(g) is present at equilibrium.
(A) I only
(B) II only
(C) Both I and II
(D) Neither I nor II
Chemistry

Which sample demonstrates particles arranged in a regular geometric pattern?

(A) CO2(g)
(B) CO2(s)
(C) CO2(l)
(D) CO2(aq)
(E) None of the above
Chemistry

2019 U.S. National Chemistry Olympiad Local Section Exam Question 13

Which gas at 600 K has the same effusion rate as methane (CH4) at 150 K?

(A) He
(B) O2
(C) SO2
(D) N2O4
Chemistry

2019 U.S. National Chemistry Olympiad Local Section Exam Question 6

Which solute, when dissolved in 1 kg H2O, will give the solution with the highest boiling point?

(A) 50 g ethylene glycol, HOCH2CH2OH
(B) 50 g hydroxyacetic acid, HOCH2COOH
(C) 50 g glycerol, HOCH2CHOHCH2OH
(D) 50 g glyoxal, HCOCHO
Chemistry

Which substance cannot be decomposed chemically?

(A) Ammonia
(B) Tellurium
(C) Methane
(D) Water
(E) Lunch