Polytechnic Chemistry 2

Question 1

What is an exothermic reaction?

Accepted Answer

A reaction that releases heat to the surroundings

Answer

Exothermic reactions release energy (usually as heat) to the surroundings, resulting in a negative enthalpy change (ΔH < 0).

Question 2

What is the molecular formula of water?

Accepted Answer

H₂O

Answer

Water has the molecular formula H₂O, consisting of two hydrogen atoms bonded to one oxygen atom.

Question 3

What does the periodic table organize elements by?

Accepted Answer

Increasing atomic number

Answer

Elements in the modern periodic table are arranged in order of increasing atomic number (number of protons).

Question 4

What type of reaction is: A + BC → AC + B?

Accepted Answer

Single displacement (substitution) reaction

Answer

In a single displacement reaction, one element replaces a similar element in a compound.

Question 5

What is a mole in chemistry?

Accepted Answer

A unit representing 6.022 × 10²³ particles

Answer

A mole is a standard unit of amount in chemistry representing 6.022 × 10²³ particles (atoms, molecules, or ions).

Polytechnic Practice Test