O level Chemistry Acid, Bases & Salts

Which statement correctly describes an acidic solution?

• It contains hydrogen ions only

• It contains more hydrogen ions than hydroxide ions

• It turns blue cobalt chloride paper pink

• It turns universal indicator blue

Substance X is mixed with ammonium chloride and heated to give ammonia gas. What could substance X be?

• sodium metal

• zinc carbonate

• calcium hydrioxide

• sulfuric acid

When solid Y was added to dilute sulfuric acid, effervescence was observed and a colourless solution was obtained. When solid Y was warmed with aqueous sodium hydroxide and potassium nitrate, a pungent gas which turned damp red litmus blue was evolved. What could Y be?

• Copper

• Zinc

• Aluminium

• Aluminium carbonate

Zinc is heated in oxygen. The product obtained is yellow when hot and white when cold. Which of the following will neutralise the product?

• aqueous sodium hydroxide

• dilute hydrochloric acid

• dilute sulfuric acid

A piece of magnesium does not react when put into a solution of hydrogen chloride in chloroform. Which of the following changes will cause a reaction of occur?

• adding a catalyst

• adding water and stirring

• increasing the temperature

• increasing the concentration of hydrogen chloride in chloroform

In a test for presence of lead (II) ions in a solution, aqueous sodium hydroxide is added slowly till excess. Which of the following diagrams shows how the mass of the precipitate varies with the volume (v) of the aqueous sodium hydroxide added?

• 
• 
• 
• 

Solutions X, Y and Z of the same concentrations were tested with a few drops of methyl orange and phenolphthalein. The results are shown in the table. What is the order of increasing pH values for the solutions?

• X, Y, Z

• X, Z, Y

• Y, X, Z

• Z, X, Y

Which method is used to prepare copper (II) chloride?

• adding copper to dilute hydrochloric acid at room temperature

• precipitating the salt by adding copper (II) carbonate to aqueous ammonium chloride

• titrating copper (II) hydroxide with dilute hydrochloric acid

• warming copper (II) oxide with dilute hydrochloric acid

12.0g of anhydrous magnesium sulfate combines with 12.6g of water to form hydrated magnesium sulfate. What is the formula of hydrated magnesium sulfate?

• MgSO₄•3H₂O

• MgSO₄•5H₂O

• MgSO₄•7H₂O

• MgSO₄•9H₂O

A student has 5 reagents:

- dilute hydrochloric acid

- dliute sulfuric acid

- dilute nitric acid

- solid calcium carbonate

-solid copper (II) carbonate

How many soluble salts can be prepared?

• 3

• 4

• 5

• 6