**Part I. Multiple/single Choice**

1) Choose the right statement abut the definition of chemistry

a) Chemistry seeks to understand the behavior of matter by studying its properties only in the macroscopic scale

b) Quantum theory is one of the scientific tools that is used in chemistry to understand the behavior of matter

c) Chemistry does not seek to understand matter behavior, only seeks to transform it

d) Chemistry disregards the behavior of matter, only focuses on thermodynamics

2) Answer true (T) or false (F) to the following statements:

a) Molecules are the elemental building blocks of matter

b) Atoms in their pure form are difficult to find in nature, they are easily found by different molecular arrangements

c) The properties of substances are strongly dependent on their atomic and molecular compositions

d) Molecules are composed by at least one atom

3) Choose the wrong statement:

a) Scientific knowledge is based on observations and experiments

b) Hypotheses are tentative interpretations of the subject of study, based on observations

c) Hypotheses never can be refuted

d) Scientific theories are the pinnacle of the scientific knowledge

4) Regarding to the definition of energy, choose the statement that best fit

a) Energy is the capacity to sustain a constant force by a certain amount of time

b) The capacity to apply a force along certain distance is defined as energy

c) Energy is the sum of potential plus kinetic energies multiplied by time

d) Energy is the product of work and time

5) Choose the right units (of the International System of units, SI) of mass and energy, respectively

a) Mole & Watt

b) Kilogram & Joule

c) gram & Joule

d) Kilogram & BTU

6) Choose the right symbols for the SI system of the prefixes multiplied correspondingly to 1012 and 10-9

a) P and m

b) T and p

c) G and a

d) T and n

7) From the Table 1.4 of lesson #2, to which material corresponds the density of 6,500 kg in 2.5 m3?

a) Gold

b) Ethanol

c) Glass

d) Water

8) In order to prepare an experiment, you weighted a reactant in a balance and read 1.0236. Which is/are the digit(s) with uncertainty/uncertainties?

a) 36

b) 6

c) 236

d) 0236

9) Choose the correct statement regarding to the certainty of data measured in a laboratory

a) We get a better certainty of data by analyzing a sample with the highest tolerated amount of significant figures

b) The amount of significant figures is irrelevant, therefore the certainty is independent of that

c) The certainty of the results depends only on the half of significant figures of a given result/datum

d) In order to get a satisfactory level of certainty in chemical experiments is only necessary 1 significant figure

10) Which is the correct scientific notation?

a) 1,600.0

b) 1,600

c) 1.6 x 103

d) 1,6 x 103

11) Which is the right result in terms of significant figures from the multiplication of 1.43 x 10-3 x 2.2 x 10-5?

a) 3.1 x 10-8

b) 3.14 x 10-8

c) 3.15 x 10-8

d) 3.2 x 10-8

12) By applying rounding and the right amount of significant figures, which is t he right results of the division of 6.42/1.041?

a) 6.2

b) 6.17

c) 6.167

d) 6.1

**Part II. Fill in the blanks** (always use scientific notation).

1) How many meters are 16 inches? ___________________

2) How many liters are 650 microliters? _____________________

3) 2,500 mm2 to nm2 (use 2 significant figures) _________________________

4) Convert 4.5 kPa to atm _________________________

5) The amount of charge of an electron, in Coulombs, is _______________________

6) The positive charge of an atom is contained in its ____________________

7) The mass of a neutron, in kg, is (give 3 significant figures) ________________________

8) The definition of the atomic number “Z” is _______________________________________

9) The mass number of the isotope of carbon with 7 neutrons is ___________

10) From the periodic table, write the symbols of two metalloids ___________________

**Part III. Calculations** (always use rounding and the right amount of significant figures)

1) Based on the periodic table, determine the mass, in kg, of Fe(II), use 3 significant figures.

2) Calculate the number of atoms in 0.1 g of Na (use the periodic table)

3) How many grams there are in 0.25 moles of NH4?

4) How many grams there are in 1 mol of benzene? (C6H6)

5) How many moles of Cl2 there are in 50 g?