IGCSE Chemistry

What is the oxidation number of Cl_²?

• 0

• +1

• +2

• -1

In which substance does bromine have an oxidation number of +1?

• Br₂

• HBr

• HBrO

• HBrO₂

Is calcium oxidized or reduced in the following reaction? 
2 CaO--> 2 Ca + O₂

• Oxidized

• Reduced

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Reduction is the ___________ of electrons.

• loss

• gain

• sharing

• transfer

Tags

NGSS.HS-PS1-1

The following chemical equation represents the extraction of silicon from quartz using coke. SiO₂ + C → Si + CO₂ What is the change in oxidation number of silicon?

• +2 to 0

• +4 to 0

• 0 to +2

• 0 to +4

Which of the following cannot occur during oxidation?

• Gain of oxygen

• Donation of electrons

• Loss of hydrogen

• Decrease in oxidation number

• -2

• 0

• -1

• +1

A craftsman is working on a new musical instrument and needs a durable yet malleable metal. He decides to create an alloy by mixing copper with another metal to produce brass. Which metal should he mix with copper?

• Zinc

• Nickel

• Chromium

• Iron

• A

• B

• C

• D

The diagram shows the electrolysis of dilute sulfuric acid.

Which substance is produced at the negative electrode?

• hydrogen

• oxygen

• sulfur dioxide

• water

Tags

NGSS.HS-PS2-5