Red
What pH value (level) indicates a neutral solution?
Answer: 7
Which ion is responsible for the acidic properties of a solution?
Answer: Hydrogen ion (H⁺)
What type of reaction breaks one compound into simpler substances?
Answer: Decomposition reaction
What color does blue litmus paper turn when placed in an acidic solution?
Answer: Red
What color does red litmus paper turn when placed in a basic solution?
Answer: Blue
Which type of chemical reaction involves the burning of a substance in the presence of oxygen?
Answer: Combustion reaction
What type of chemical reaction occurs when two substances combine to form one product?
Answer: Synthesis (Combination) reaction
What is the pH range of acids?
Answer: Less than 7 or 0 to 6
Give one observable sign that a chemical reaction has occurred.
Any one of the following:
In the reaction
Zn + CuSO₄ → ZnSO₄ + Cu,
what type of reaction is represented?
Answer: Single replacement reaction
Indicators obtained from plants are called what type of indicators?
Answer: Natural indicators
What is the main product formed when an acid reacts with a base, aside from water?
Answer: Salt
In the equation
2Mg + O₂ → 2MgO,
identify the type of chemical reaction.
Answer: Synthesis (Combination) reaction
Classify the reaction:
BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)
Answer: Double replacement reaction
What is the color of the blue litmus paper after placing in a basic solution?
Answer: Blue
Indicators made in laboratories are called what type of indicators?
Answer: Synthetic indicators
What type of reaction occurs when methane burns in oxygen?
Answer: Combustion reaction
Name the salt produced when hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH).
Answer: Sodium chloride (NaCl)
Why are indicators useful in chemistry?
Answer: They help determine whether a solution is acidic, basic, or neutral by changing color.
What type of ion is produced by bases in water?
Answer: Hydroxide ions (OH⁻)
Explain why color change alone does not always prove a chemical reaction has occurred.
Answer: Because some physical changes (such as mixing colored substances or dissolving dyes) can also produce color changes without forming a new substance.
Give 2 examples of a synthetic indicator.
Any one of the following:
Which indicator turns pink in a basic solution?
Answer: Phenolphthalein
Give 3 examples of a natural indicator.
Answer: Any one of the following:
A student observes bubbles after mixing vinegar and baking soda. Why do these bubbles indicate a chemical reaction rather than a physical change?
Answer: Because a new substance (carbon dioxide gas) is produced.