CSS - PMS - CCE - PCS - General Science
Chemical Reactions - Bases
Which is a common strong base?
A. Hydrochloric acid
B. Carbon dioxide
C. Sodium hydroxide
D. Acetic acid
Correct Answer: C
Sodium hydroxide dissociates extensively in water to yield hydroxide ions.
CSS - PMS - CCE - PCS - General Science
Chemical Reactions - Bases
What pH is generally characteristic of a basic aqueous solution?
A. Exactly 7 only
B. Always 0
C. Less than 7
D. Greater than 7
Correct Answer: D
Basic solutions have pH values above 7 under standard classroom conditions.
CSS - PMS - CCE - PCS - General Science
Chemical Reactions - Bases
What color does red litmus generally turn in a basic solution?
A. Red
B. Blue
C. Yellow
D. Colorless always
Correct Answer: B
Bases turn red litmus blue.
CSS - PMS - CCE - PCS - General Science
Chemical Reactions - Bases
According to the Arrhenius definition, a base increases the concentration of which ion in water?
A. OH− ions
B. CO2 molecules
C. Cl− ions
D. H+ ions
Correct Answer: A
Arrhenius bases increase hydroxide ion concentration in aqueous solution.
CSS - PMS - CCE - PCS - General Science
Chemical Reactions - Acids
Which term describes an acid that ionizes only partially in water?
A. Weak acid
B. Strong base
C. Neutral salt
D. Oxidizing metal
Correct Answer: A
Weak acids establish an equilibrium and do not ionize completely in water.
CSS - PMS - CCE - PCS - General Science
Chemical Reactions - Acids
Which acid is found naturally in citrus fruits?
A. Perchloric acid
B. Hydrofluoric acid
C. Sulfuric acid
D. Citric acid
Correct Answer: D
Citrus fruits contain citric acid.
CSS - PMS - CCE - PCS - General Science
Chemical Reactions - Acids
Which gas is released when an acid reacts with a carbonate?
A. Oxygen
B. Ammonia
C. Hydrogen only
D. Carbon dioxide
Correct Answer: D
Acid-carbonate reactions form a salt, water and carbon dioxide.
CSS - PMS - CCE - PCS - General Science
Chemical Reactions - Acids
Which gas is commonly released when many acids react with reactive metals?
A. Chlorine
B. Hydrogen
C. Nitrogen
D. Helium
Correct Answer: B
Acids can react with sufficiently reactive metals to form a salt and hydrogen gas.
CSS - PMS - CCE - PCS - General Science
Chemical Reactions - Acids
What products are typically formed when an acid reacts with a base?
A. Only hydrogen gas
B. Only oxygen gas
C. Metal and carbon
D. Salt and water
Correct Answer: D
Acid-base neutralization commonly yields salt and water.
CSS - PMS - CCE - PCS - General Science
Chemical Reactions - Acids
What pH is generally characteristic of an acidic aqueous solution at ordinary conditions?
A. Always 14
B. Less than 7
C. Greater than 7
D. Exactly 7
Correct Answer: B
Acidic solutions have pH below 7 under standard classroom conventions.
CSS - PMS - CCE - PCS - General Science
Chemical Reactions - Acids
What color does blue litmus paper generally turn in an acidic solution?
A. Blue
B. Black
C. Green
D. Red
Correct Answer: D
Acids turn blue litmus red.
CSS - PMS - CCE - PCS - General Science
Chemical Reactions - Acids
Which acid is the main acid in vinegar?
A. Hydrochloric acid
B. Citric acid
C. Acetic acid
D. Sulfuric acid
Correct Answer: C
Vinegar contains dilute acetic acid.
CSS - PMS - CCE - PCS - General Science
Chemical Reactions - Acids
Which acid is present in gastric juice?
A. Hydrochloric acid
B. Sulfuric acid
C. Acetic acid only
D. Nitric acid
Correct Answer: A
The stomach secretes hydrochloric acid as part of gastric juice.
CSS - PMS - CCE - PCS - General Science
Chemical Reactions - Acids
According to the Arrhenius definition, an acid increases the concentration of which ion in aqueous solution?
A. OH− ions
B. H+ (or H3O+) ions
C. Cl− ions only
D. Na+ ions only
Correct Answer: B
Arrhenius acids increase hydrogen ion or hydronium ion concentration in water.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Mixtures
Which mixture of metals is called an alloy?
A. A metallic mixture such as brass
B. Sodium chloride crystal
C. Distilled water
D. Pure oxygen
Correct Answer: A
Alloys are mixtures containing a metal and one or more other elements; brass is mainly copper and zinc.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Mixtures
Does a mixture have a fixed composition?
A. Only if it is a gas
B. Only if it is colored
C. No
D. Yes, always
Correct Answer: C
The relative amounts of components in a mixture can vary.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Mixtures
What property mainly allows evaporation to recover a dissolved solid from solution?
A. The solute is always magnetic
B. The solvent has no mass
C. The solvent is more volatile than the solute
D. The solute becomes an element
Correct Answer: C
Evaporation removes volatile solvent, leaving less volatile dissolved material behind.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Mixtures
Which separation technique is widely used to separate colored components in inks?
A. Crystallization only
B. Magnetic separation
C. Chromatography
D. Sedimentation only
Correct Answer: C
Chromatography separates components based on differing affinities for stationary and mobile phases.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Mixtures
How can iron filings be separated from sulfur powder before they react?
A. By adding more sulfur
B. Using a magnet
C. By melting both together
D. By electrolysis of air
Correct Answer: B
Iron is magnetic whereas sulfur is not.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Mixtures
Which method is suitable for separating liquids with different boiling points?
A. Filtration
B. Decanting solids only
C. Magnetization only
D. Distillation
Correct Answer: D
Distillation separates substances based on volatility and boiling-point differences.