Grade 9 - Energy and Reactions

Many chemical reactions that cause explosion need ___________

• carbon dioxide

• oxygen

• nitrogen

• potassium

Explosive usually have _____________ to supply the oxygen needed.

• oxidising agent

• potasium nitrate

• carbon dioxide

Which one of the following sentence is true for "oxidiser"?

• releases oxygen

• chemically mixing with oxygen

• break bond with oxygen

Which one of the following oxidising agent is mixed with charcoal to make gunpowder?

• sodium nitrate

• calcium nitrate

• potassium nitrate

What happens when heat is given to potassium nitrate?

• it will explode

• it will catch fire

• it will release oxygen during thermal decomposition

How can we test that the released gas in potassium nitrate is oxygen?

• through calcium hydroxide

• lime water testing

• by bringing a glowing splint near the gas

What steps needs to be taken to make the explosion react quicker?

• release large amount of oxygen

• break down the solid fuel into tiny pieces.

• all the above

Which one of the following sentence is true about energy?

• once energy is transferred, it is destroyed completely.

• energy can only be transferred from solid to gas.

• energy can be destroyed with high power lasers.

• energy can neither be destroyed or created, it only gets transferred from one source to another.

What is the difference between exothermic and endothermic reaction?

Which one of the following is an example of endothermic reaction?

• combustion

• thermal decomposition

• neutralisation