Upload
ruel-cedeno
View
14
Download
1
Embed Size (px)
DESCRIPTION
Chemistry and Physics Multiple choice test
Citation preview
General Chemistry Questions
1.) Silver chromate solid exists in equilibrium with Ag+ and CrO42- according to:
Ag2CrO4 (s) 2 Ag+ (aq) + CrO4
2- (aq)
If silver nitrate is added to this solution,
A) a precipitate of Ag2CrO4 forms.
B) the solution get increasingly blue.
C) the concentration of CrO42- increases.
D) the [Ag2CrO4] increases.
E) the common ion effect does not apply.
Solution:
According to Le Chatelier’s principle, a system at equilibrium will shift to the direction
that will minimize the effect of the disturbance. Since addition of AgNO3 will result to
formation of Ag+, the reaction will proceed to use up the added Ag+ forming more Ag2CO3.
2.) What is the mass of an impure sodium chloride sample must be taken for analysis so
that the weight of silver chloride precipitate obtained in mg will be equal to the %Cl in
the sample?
a. 19.76mg b. 12.66mg c. 24.73mg d. 4.04mg
Solution:
35.45
107.87 35.45% 100%
35.45100 24.73
107.87 35.45
AgCl
AgCl
Let x weight of NaCl
Weight
Cl x Weightx
x x mg
3.) A 250 mg sample containing 45% MgCO3 and 55% CaCO3 was ignited producing CO2
as decomposition product. Assuming that the decomposition reaction is complete, .what
is the change in weight of a NaOH solution used to absorb CO2?
a. 58.73 mg b. 47.70 mg c. 119.24 mg d. 60.51 mg
Solution:
Write the equations involved in the decomposition reaction.
3 2
3 2
2
44 440.55(250mg) 0.45(250 ) 119.24
100 84.31
MgCO MgO CO
CaCO CaO CO
CO mg mg
4.) A compound whose molecules are not associated by hydrogen bonding is
a. CH3CH2OH b. (CH3)2NH c. HCOOH d. (CH3)3COCH3
Solution:
Compounds whose H are not attached to highly electronegative atom (such as O and N)
are not associated with hydrogen bonding. All hydrogen atoms (CH3) 3COCH3 are
attached to C. Hence, it’s not capable of hydrogen bonding.
5.) The pH of a Ba(OH)2 solution is 10.0. What is the .H+ ion concentration?
a. 4.0 x 1011 M b. 1.6 x 10-10 M c. 1.3 x 10-5 M d. 1.0 x 10-10 M
Solution:
Since pH=-log[H+] 10 10[ ] 10 1 10H x
6.) Which of the following does not assume the behavior of ideal gases?
a. Boyle's Law b. Vander Waals Equation
c. Graham's Law of Diffusion d. Dalton's Law of Partial Pressure
Solution:
van der Waals Equation accounts for intermolecular attraction and volume occupied
by the gas molecules. The rest are based on ideal behavior of gases.
7.) Which of the following bonds is the strongest?
a. Covalent Bond b. Hydrogen Bond c. Ionic Bond d. Dative Bond
Solution:
Ionic bond is the strongest because of the strong attraction and opposite charges.
8.) Which of the following molecules/compounds is formed by covalent bonds?
a. LiF b. MgO c. ZnS d. NO2
Solution:
NO2 is formed by covalent bonding because it is composed of two nonmetals.
9.) The atomic weight of chlorine is 35.45 and its naturally occurring isotopes are Cl-35
and Cl-37. What is the percentage abundance ofCl-35?
a. 95.8% b. 98.7% c. 77.5% d. 75.0%
Solution:
35.45 (35) (1 )(37)
0.775 77.5%
x x
x
PHYSICS QUESTIONS
1. In uniform circular motion with constant speed, which of following statement is/are true
about its velocity?
I. Magnitude and Direction remains constant
II. Changes
III. Only Direction remains constant
IV. Only Magnitude remains constant
a) I only
b) II and III
c) III only
d) II and IV
Explanation:
In uniform circular motion, the speed is constant but the direction changes. Hence, the
velocity changes while the magnitude remains constant.
2. Which of the following is true about mechanical equilibrium?
I. It is moving at constant velocity
II. Net external torque is constant
III. Net external force is zero
IV. Net external torque is zero.
a.) I only
b.) III and IV
c.) I,III and IV
d.) II, III, nd IV
Explanation:
For a system to be in mechanical equilibrium, the net force and net external torque must be
zero. Also, from Newton’s law, if the velocity is constant, then there is no acceleration,
consequently the body is in mechanical equilibrium. Hence, the correct statements are I, III,
and IV.
3. Which of the following is true about rotational inertia?
I. depends on angular velocity
II. Analogous to mass in linear motion
III. depends on the density
IV. Depends on mass distribution about the axis
a.) II only
b.) II and IV
c.) III and IV
d.) IV only
Explanation:
For linear motion, the quantity that resists motion is mass. In rotational motion, the quantity
that resists rotation is rotational inertia. Hence, it is analogous to mass in linear motion.
Furthermore, the rotational inertia varies for different geometric forms because it is
dependent upon the mass distribution about the axis. Hence, the correct statements are II and
IV.
4. Which of the following is related to buoyancy?
a) Archimedes Principle
b) Pascal’s Law
c) Bernoulli’s Principle
d) Boyle’s Law
Explanation:
Archimedes principle states that for a floating object, the buoyant force is equal to the
weight of the object or the weight of the fluid displaced. Pascal’s Law states that pressure is
transmitted undiminished in all directions for a confined fluid. Bernoulli’s Principle is an energy
balance in fluid systems. Boyle’s Law states that for gases at constant temperature, the pressure
varies inversely as volume. Hence, the correct answer is Archimedes Principle.
5.) Which of the following statements is/are true about angular momentum?
I. It is conserved when there are no internal torques
II. It is conserved when net external torque is zero
III. It is conserved when external torques are conservative
IV. It is conserved when net external torque is constant
a) I only
b) II only
c) II and III
d) II and IV
Explanation:
Angular momentum is conserved if and only if the net external torque is zero. Hence, the answer
is II only.