CSS - PMS - CCE - PCS - General Science
Acid/Base
The main acid in vinegar is:
A. Acetic acid
B. Citric acid
C. Lactic acid
D. Sulfuric acid
Correct Answer: A
A: Correct because vinegar is a dilute aqueous solution containing acetic acid. B: Incorrect because citric acid is common in citrus fruits. C: Incorrect because lactic acid is associated with sour milk and muscles. D: Incorrect because sulfuric acid is a strong mineral acid not used as the main acid in vinegar.
CSS - PMS - CCE - PCS - General Science
Acid/Base
Baking soda has the chemical formula:
A. Na₂CO₃
B. NaHCO₃
C. NaOH
D. K₂CO₃
Correct Answer: B
A: Incorrect because Na₂CO₃ is sodium carbonate or soda ash. B: Correct because baking soda is sodium hydrogen carbonate, NaHCO₃. C: Incorrect because NaOH is caustic soda. D: Incorrect because K₂CO₃ is potassium carbonate.
CSS - PMS - CCE - PCS - General Science
Acid/Base
Tooth enamel begins to dissolve significantly when mouth pH falls below about:
A. 9.5
B. 7.5
C. 5.5
D. 13
Correct Answer: C
A: Incorrect because 9.5 is basic. B: Incorrect because 7.5 is slightly basic. C: Correct because tooth enamel demineralization increases when plaque pH falls below roughly 5.5. D: Incorrect because 13.0 is strongly basic.
CSS - PMS - CCE - PCS - General Science
Acid/Base
Antacids relieve acidity mainly by:
A. Neutralizing excess stomach acid
B. Producing more HCl
C. Stopping all digestion permanently
D. Increasing carbon dioxide in blood
Correct Answer: A
A: Correct because antacids contain mild bases that neutralize excess gastric acid. B: Incorrect because producing more HCl would worsen acidity. C: Incorrect because they do not permanently stop all digestion. D: Incorrect because raising blood carbon dioxide is not their intended action.
CSS - PMS - CCE - PCS - General Science
Acid/Base
The main acid present in the human stomach is:
A. Hydrochloric acid
B. Sulfuric acid
C. Acetic acid
D. Nitric acid
Correct Answer: A
A: Correct because gastric juice contains hydrochloric acid, which aids digestion and helps kill microbes. B: Incorrect because sulfuric acid is not a normal stomach acid. C: Incorrect because acetic acid is the main acid in vinegar. D: Incorrect because nitric acid is not normally secreted in the stomach.
CSS - PMS - CCE - PCS - General Science
Acid/Base
Acid rain is mainly associated with atmospheric oxides of:
A. Sulfur and nitrogen
B. Sodium and potassium
C. Calcium and magnesium
D. Helium and neon
Correct Answer: A
A: Correct because sulfur oxides and nitrogen oxides form acids in the atmosphere and contribute to acid rain. B: Incorrect because sodium and potassium oxides are not the main atmospheric cause. C: Incorrect because calcium and magnesium compounds can help neutralize acidity. D: Incorrect because helium and neon are noble gases and do not form acid-rain oxides under normal conditions.
CSS - PMS - CCE - PCS - General Science
Acid/Base
Which hydroxide is amphoteric?
A. NaOH
B. KOH
C. Al(OH)₃
D. Ba(OH)₂
Correct Answer: C
A: Incorrect because NaOH is a strong base. B: Incorrect because KOH is a strong base. C: Correct because Al(OH)₃ can react with both acids and strong bases. D: Incorrect because Ba(OH)₂ is a strong base when dissolved.
CSS - PMS - CCE - PCS - General Science
Acid/Base
Which oxide is amphoteric?
A. Al₂O₃
B. SO₃
C. K₂O
D. CO₂
Correct Answer: A
A: Correct because Al₂O₃ reacts with both acids and strong bases, so it is amphoteric. B: Incorrect because SO₃ is acidic. C: Incorrect because K₂O is basic. D: Incorrect because CO₂ is acidic.
CSS - PMS - CCE - PCS - General Science
Acid/Base
Which of the following is a basic oxide?
A. SO₂
B. CO₂
C. MgO
D. P₄O₁₀
Correct Answer: C
A: Incorrect because SO₂ is acidic. B: Incorrect because CO₂ is acidic. C: Correct because MgO is a metal oxide that reacts with acids and is classified as basic. D: Incorrect because P₄O₁₀ is an acidic oxide.
CSS - PMS - CCE - PCS - General Science
Acid/Base
Which of the following is an acidic oxide?
A. CO₂
B. MgO
C. Na₂O
D. CaO
Correct Answer: A
A: Correct because CO₂ is a nonmetal oxide that forms carbonic acid in water and reacts with bases. B: Incorrect because MgO is a basic metal oxide. C: Incorrect because Na₂O is strongly basic. D: Incorrect because CaO is a basic oxide.
CSS - PMS - CCE - PCS - General Science
Acid/Base
A basic oxide commonly reacts with an acid to form:
A. Salt and water
B. Only hydrogen
C. Only carbon dioxide
D. Another acid only
Correct Answer: A
A: Correct because basic oxides neutralize acids, usually producing salt and water. B: Incorrect because hydrogen is not the sole neutralization product. C: Incorrect because carbon dioxide is not produced from every basic oxide. D: Incorrect because the reaction does not normally produce only another acid.
CSS - PMS - CCE - PCS - General Science
Acid/Base
An acid reacting with a metal oxide generally forms:
A. Salt and water
B. Hydrogen and salt
C. Carbon dioxide only
D. A metal and an acid
Correct Answer: A
A: Correct because many metal oxides are basic and react with acids to form salt and water. B: Incorrect because hydrogen is usually associated with acid–metal reactions. C: Incorrect because carbon dioxide is associated with acid–carbonate reactions. D: Incorrect because metal and acid are not the normal products.
CSS - PMS - CCE - PCS - General Science
Acid/Base
Which gas turns limewater milky?
A. Hydrogen
B. Oxygen
C. Carbon dioxide
D. Nitrogen
Correct Answer: C
A: Incorrect because hydrogen does not form calcium carbonate. B: Incorrect because oxygen does not give the limewater test. C: Correct because carbon dioxide reacts with limewater to form insoluble calcium carbonate, causing milkiness. D: Incorrect because nitrogen is generally unreactive in this test.
CSS - PMS - CCE - PCS - General Science
Acid/Base
An acid reacting with a carbonate usually produces:
A. Salt, water, and carbon dioxide
B. Salt and hydrogen only
C. Metal and oxygen
D. Base and chlorine
Correct Answer: A
A: Correct because acid–carbonate reactions produce a salt, water, and carbon dioxide. B: Incorrect because hydrogen is typical of many acid–metal reactions. C: Incorrect because metal and oxygen are not products of acid–carbonate reactions. D: Incorrect because a base and chlorine are not the expected products.
CSS - PMS - CCE - PCS - General Science
Acid/Base
An acid reacting with a suitable active metal usually produces:
A. Salt and hydrogen gas
B. Salt and oxygen gas
C. Base and nitrogen gas
D. Only water
Correct Answer: A
A: Correct because many acids react with active metals to form a salt and hydrogen gas. B: Incorrect because oxygen is not the normal gas in this reaction. C: Incorrect because a base and nitrogen are not typical products. D: Incorrect because water alone is not produced.
CSS - PMS - CCE - PCS - General Science
Acid/Base
What are the products of HCl + NaOH?
A. NaCl and H₂O
B. Na₂SO₄ and H₂
C. Cl₂ and Na
D. HNO₃ and KOH
Correct Answer: A
A: Correct because hydrochloric acid neutralizes sodium hydroxide to form sodium chloride and water. B: Incorrect because sodium sulfate requires sulfuric acid, and hydrogen is not a neutralization product. C: Incorrect because chlorine and sodium metal are not formed in this aqueous neutralization. D: Incorrect because nitric acid and potassium hydroxide are unrelated substances.
CSS - PMS - CCE - PCS - General Science
Acid/Base
A neutralization reaction generally produces:
A. Salt and water
B. Hydrogen and oxygen
C. Only carbon dioxide
D. Metal and acid
Correct Answer: A
A: Correct because an acid reacting with a base generally forms salt and water. B: Incorrect because hydrogen and oxygen are not the usual products of neutralization. C: Incorrect because carbon dioxide forms when acids react with carbonates, not in every neutralization. D: Incorrect because metal and acid are reactants in another reaction type, not products.
CSS - PMS - CCE - PCS - General Science
Acid/Base
Which indicator gives an approximate pH over a wide range?
A. Universal indicator
B. Blue litmus only
C. Phenolphthalein only
D. Methyl orange only
Correct Answer: A
A: Correct because a universal indicator contains a mixture of indicators and shows different colors across a broad pH range. B: Incorrect because blue litmus mainly distinguishes acidic from non-acidic conditions. C: Incorrect because phenolphthalein changes over a limited basic range. D: Incorrect because methyl orange changes over a limited acidic range.
CSS - PMS - CCE - PCS - General Science
Acid/Base
Methyl orange is typically what color in a basic solution?
A. Red
B. Yellow
C. Pink
D. Colorless
Correct Answer: B
A: Incorrect because red is its acidic color. B: Correct because methyl orange is yellow in basic solution. C: Incorrect because pink is associated with phenolphthalein in base. D: Incorrect because methyl orange is not normally colorless in base.
CSS - PMS - CCE - PCS - General Science
Acid/Base
Methyl orange is typically what color in an acidic solution?
A. Yellow
B. Red
C. Blue
D. Purple
Correct Answer: B
A: Incorrect because yellow is its basic color. B: Correct because methyl orange is red in acidic solution. C: Incorrect because blue is not a methyl-orange color. D: Incorrect because purple is not its standard acidic color.