UA 8 Retest

Look at the circle graph of the different elements in Earth's crust.

Based on the graph, which conclusion can be drawn about the elements in Earth's Crust? (6.5B)

• Iron is more abundant than sodium.

• Silicon is more abundant than oxygen.

• Aluminum is more abundant than silicon.

• Calcium is more abundant than magnesium.

A scientist isolates an element during an experiment. How can he know that it is an element? (6.5C)

• It is made up of only one type of atom.

• It is made up of exactly two types or atoms.

• It is in the periodic table.

• It has characteristics.

How many elements are involved in the reaction shown below? (6.5A)

C3H8+5O2---------- 3CO2 + 4H20

• 7 elements

• 3 elements

• 17 elements

• 19 elements

Lorena is in the lab trying to demonstrate that she is capable to create a new substance during his experiments. What are the sign of the formation of a new substance? (6.5C)

• A chemical reaction where color and temperature change.

• A chemical reaction where formation of gas, change of color, and precipitate happens.

• A chemical reaction where a formation of gas, change of color, change of temperature, it precipitates, change of odor might happen.

• A chemical reaction where a formation of a new substance happens.

What of these is evidence that a chemical reaction has occurred? (6.5C)

• create gas (bubbling)

• precipite (creation of a solid)

• change of temperature

• change of color

How would you describe the nucleus of an atom?

• dense, positively charged

• large, positively charged

• tiny, negatively charged

• dense, negatively charged

At the atomic level, what makes elements reactive?

• having a filled outer level

• exchanging or sharing valence electrons

• having the same number of electrons

• having the same number of protons

Look at the column, taken from the periodic table. Which of the following statements is correct for the elements shown?

• Lithium has 6.9 protons.

• Lithium has the least number of protons.

• Sodium has the most number of protons.

• Potassium has 39.1 protons.

An atom has 12 protons, 14 neutrons, and 12 electrons. What is the atomic number of this element?

• 24

• 26

• 12

• 38

The element sulfur (S) has an atomic number of 16, an atomic mass of 32.1, and is on the right side of the zigzag on the periodic table. Based on this information, to which class of elements does sulfur most likely belong?

• metals

• nonmetals

• metalloids

• solids