Stemscopes Exam Chemistry Fundamentals 3

Question 1

Which of the following is a pure substance?

Accepted Answer

Gold

Answer

Gold is a pure substance because it consists of only one type of atom (Au) with uniform composition.

Question 2

What is the term for the energy needed to start a chemical reaction?

Accepted Answer

Activation energy

Answer

Activation energy is the minimum energy required to initiate a chemical reaction.

Question 3

Elements in the same group (column) of the periodic table share which property?

Accepted Answer

Same number of valence electrons

Answer

Elements in the same group have the same number of valence electrons, which gives them similar chemical properties.

Question 4

What type of reaction produces a precipitate?

Accepted Answer

Double displacement reaction

Answer

Double displacement reactions can produce a precipitate when two ionic compounds in solution exchange ions to form an insoluble product.

Question 5

Acids have a pH:

Accepted Answer

Less than 7

Answer

Acids have a pH less than 7, indicating a higher concentration of hydrogen ions (H⁺) in solution.

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