Sec 2 Chemical reactions, Acids

Choose all that apply to chemical changes:

• No new substances are formed

• New substances are formed

• Energy is sometimes taken in or given out

• The changes are easily reversed

Choose all that are correct:

Mixing salt and water is considered a physical change because

• no new substances are formed.

• we have to physically stir while mixing

• salt and water can be easily separated by evaporation or distillation

To power a vehicle,

petrol is burnt with oxygen, producing carbon dioxide, water. This process gives off a lot of heat.

Choose the correct word equation for the above process.

• petrol + oxygen → carbon dioxide + water

• petrol + carbon dioxide → oxygen + water

• Heat + petrol → carbon dioxide and water

• Petrol + oxygen → heat + water

A word equation shows the ____________ and ____________ of a chemical reaction.

A → B + C + D

The above reaction shows

When a wooden log is burnt in oxygen, the total mass of the ashes and gases produced is equal to the mass of the log and oxygen reacted.

This proves that mass is _______________ in chemical reactions.

Choose the correct statement for the picture.

• The number of atoms of each element is the same before and after the reaction. Mass is conserved.

• The arrangement of the atoms before and after the reaction is different. Mass is not conserved.

Gas X is produced during a reaction. It extinguishes a lighted splint with a 'pop' sound.

What is X?

Gas Y is colourless and odourless. It forms a white precipitate in limewater.

What is Y?

Choose all that are correct:
Blue and red litmus papers can confirm whether a solution is

• acidic

• alkaline

• neutral

• spicy