Grade 8 second semester A Chemistry Review

How to say "可逆的" in English

• revenue

• reversible

• reversion

• revertible

Which of the following is the definition of Combustion Reactions

• The substances you end up with are different from the ones you started with.

• The change is usually difficult to reverse. At the end of the reaction, you cannot easily get back the substances you started with.

• Any reaction in which a substance reacts quickly with oxygen, and gives out heat and light

• a ceramic or metal container in which metals or other substances may be melted or subjected to very high temperatures

Hydrochloric acid + magnesium → ? + ?​

• Magnesium + water

• Magnesium Chloride + Hydrogen

• Magnesium Hydroxide + Chlorine

• Magnesium Chloride + Hydroxide

Magnesium + oxygen → Magnesium oxide​

Carbon + oxygen → Carbon dioxide​

The arrow means What

• become reactant

• reversible

• react

• react to make

what is (aq) mean

• containing water; like water

• a tank or pool or bowl filled with water for keeping live fish and underwater animals

• react with water

• to show that a substance is dissolved in

Acid + Alkali ​——> ?

• Salt + water

• Salt + metal

• Salt + non-metal

• metal + water

What is the flame colour of the sodium chloride

• yellow

• blue

• lilac

• Blue-green

Na(s) + H2O   $\longrightarrow$  NaOH  +  ...........

• CO2

• H2O

• H2

• O2

________and_________make up the nucleus.​

• Neutron and electron

• electron and proton

• Neutron and proton

• Atom and electron

Why do atoms have no electric charge? ​

• This is because, in any ions, the number of protons is the same as the number of electrons.

• This is because, in any atom, the number of protons is the same as the number of electrons.

• This is because, in any atom, the number of electrons is the same as the number of neutrons.

• This is because, in any atom, the number of neutron is the same as the number of protons.