Science

Correct answer: A

I is correct: Vinegar's characteristic acid → Acetic acid. Vinegar is a dilute aqueous solution containing this acid. II is incorrect: Gypsum → Calcium sulphate dihydrate. Its formula is CaSO4·2H2O.

Correct answer: C

Their formula is Na2CO3·10H2O.

Correct answer: B

I is incorrect: Plaster of Paris → Calcium sulphate hemihydrate. Its formula is CaSO4·½H2O. II is incorrect: Main acid in citrus fruits → Citric acid. It contributes to their sour taste.

Correct answer: A

I is correct: Gypsum → Calcium sulphate dihydrate. Its formula is CaSO4·2H2O. II is incorrect: Principal gas in ordinary natural gas → Methane. Natural gas is a hydrocarbon mixture dominated by methane.

Correct answer: D

Bacterial fermentation produces lactic acid from sugars.

Correct answer: A

I is correct: Washing soda crystals → Sodium carbonate decahydrate. Their formula is Na2CO3·10H2O. II is incorrect: Quicklime → Calcium oxide. Its formula is CaO.

Correct answer: B

I is incorrect: Main acid in citrus fruits → Citric acid. It contributes to their sour taste. II is correct: Vinegar's characteristic acid → Acetic acid. Vinegar is a dilute aqueous solution containing this acid.

Correct answer: D

I is incorrect: Gypsum → Calcium sulphate dihydrate. Its formula is CaSO4·2H2O. II is incorrect: Slaked lime → Calcium hydroxide. Its formula is Ca(OH)2.

Correct answer: D

Its formula is CaSO4·½H2O.

Correct answer: A

I is correct: Main acid in citrus fruits → Citric acid. It contributes to their sour taste. II is correct: Principal gas in ordinary natural gas → Methane. Natural gas is a hydrocarbon mixture dominated by methane.

Correct answer: D

I is correct: Gypsum → Calcium sulphate dihydrate. Its formula is CaSO4·2H2O. II is incorrect: Washing soda crystals → Sodium carbonate decahydrate. Their formula is Na2CO3·10H2O.

Correct answer: C

Vinegar is a dilute aqueous solution containing this acid.

Correct answer: B

I is incorrect: Acid commonly found in curd → Lactic acid. Bacterial fermentation produces lactic acid from sugars. II is incorrect: Main acid in citrus fruits → Citric acid. It contributes to their sour taste.

Correct answer: B

I is incorrect: Vinegar's characteristic acid → Acetic acid. Vinegar is a dilute aqueous solution containing this acid. II is correct: Plaster of Paris → Calcium sulphate hemihydrate. Its formula is CaSO4·½H2O.

Correct answer: D

I is correct: Slaked lime → Calcium hydroxide. Its formula is Ca(OH)2. II is correct: Main acid in citrus fruits → Citric acid. It contributes to their sour taste.

Correct answer: C

Its formula is CaSO4·2H2O.

Correct answer: D

I is incorrect: Acid commonly found in curd → Lactic acid. Bacterial fermentation produces lactic acid from sugars. II is incorrect: Slaked lime → Calcium hydroxide. Its formula is Ca(OH)2.

Correct answer: C

I is incorrect: Vinegar's characteristic acid → Acetic acid. Vinegar is a dilute aqueous solution containing this acid. II is correct: Baking soda → Sodium hydrogen carbonate. Its formula is NaHCO3.

Correct answer: D

Its formula is CaO.

Correct answer: A

I is incorrect: Plaster of Paris → Calcium sulphate hemihydrate. Its formula is CaSO4·½H2O. II is correct: Acid commonly found in curd → Lactic acid. Bacterial fermentation produces lactic acid from sugars.

Correct answer: B

I is incorrect: Gypsum → Calcium sulphate dihydrate. Its formula is CaSO4·2H2O. II is incorrect: Baking soda → Sodium hydrogen carbonate. Its formula is NaHCO3.

Correct answer: D

Its formula is NaHCO3.

Correct answer: C

I is correct: Washing soda crystals → Sodium carbonate decahydrate. Their formula is Na2CO3·10H2O. II is correct: Acid commonly found in curd → Lactic acid. Bacterial fermentation produces lactic acid from sugars.

Correct answer: C

I is incorrect: Gypsum → Calcium sulphate dihydrate. Its formula is CaSO4·2H2O. II is correct: Acid commonly found in curd → Lactic acid. Bacterial fermentation produces lactic acid from sugars.

Correct answer: D

The zinc layer helps protect iron against corrosion.