A piece of calcium is added to cold water.

Which equation represents the reaction?

• Ca + H₂O --> CaO + H₂

• Ca + 2H₂O --> Ca(OH)₂ + H₂

• 2Ca + 2H₂O --> 2CaOH + H₂

• Ca²⁺ + 2H₂O --> Ca(OH)₂ + 2H⁺

Which statement about hydrogen is not correct?

• It gives a loud squeaky pop with a glowing splint.

• It is formed when sodium metal reacts with cold water.

• It is manufactured by cracking of an alkane.

• It is used to make ammonia.

Which substance produces hydrogen gas when it reacts with dilute hydrochloric acid?

• magnesium

• magnesium carbonate

• magnesium hydroxide

• magnesium oxide

Which metal does not react with dilute hydrochloric acid to give hydrogen?

• copper

• iron

• magnesium

• zinc

Which pair of substances does not produce hydrogen gas?

• calcium and sulfuric acid

• copper and water

• sodium and water

• zinc and hydrochloric acid

Which row describes a method for making hydrogen, a use of hydrogen, and a test for hydrogen?

• A

• B

• C

• D

In which tube is hydrogen formed?

• A

• B

• C

• D

Which statement about hydrogen is not correct?

• Hydrogen is used as a rocket fuel.

• Hydrogen reacts with ethane to produce ethene.

• Sodium reacts with water to produce hydrogen.

• Water is formed when a lighted splint is placed in a gas jar of hydrogen.

Which statement about hydrogen is correct?

• It is produced when an acid reacts with a metal carbonate.

• It is produced when an acid reacts with a reactive metal.

• It is produced when an alkali reacts with an ammonium salt.

• It is produced when oxygen reacts with a hydrocarbon.

A number of different reactions produce hydrogen gas.

Which pair of reactions both produce hydrogen?

• A

• B

• C

• D