Narrowing the Choices
If after reading all the answer choices you are not sure which one is correct, eliminate those answers that you know are wrong. In the question below, first eliminate the answers that require a whole number. Then focus on the remaining choices.
The number 12.011 is the
atomic number for carbon.
mass number for carbon.
atomic mass of carbon-12.
average atomic mass of carbon.
percentage of carbon-12 in nature.
(Answer: D)
Choose the letter that best answers the question or completes the statement.
Which elements are as reactive as alkali metals?
alkaline earth metals
halogens
noble gases
transition metals
metalloids
How many valence electrons do atoms of oxygen and sulfur have?
2
4
6
8
10
Moving across a period from left to right,
elements become less metallic.
elements become more metallic.
elements become more reactive.
elements become less reactive.
elements have fewer valence electrons.
Which statement best describes nonmetals?
Nonmetals are good conductors of heat and electric current.
Nonmetals are brittle solids.
Many general properties of nonmetals are opposite to those of metals.
Nonmetals are located on the left side of the periodic table.
All nonmetals are extremely reactive.
Use this portion of the periodic table to answer Questions 5−7.
Which list of elements contains only metalloids?
aluminum and gallium
silicon and germanium
phosphorus and arsenic
aluminum, silicon, and phosphorus
gallium, germanium, and arsenic
Which elements did Mendeleev leave spaces for in his first periodic table?
(A) aluminum and phosphorus
aluminum and germanium
silicon and arsenic
gallium and germanium
gallium and aluminum
Which of the elements are among the most abundant in Earth's crust?
(A) silicon and phosphorus
aluminum and phosphorus
phosphorus and arsenic
gallium and arsenic
aluminum and silicon