EASY
Diploma
IMPORTANT
Earn 100

Outline why is PCB considered “dioxin like”, but not a dioxin.

Important Questions on Materials

EASY
Diploma
IMPORTANT
LDPE has a specific gravity of 0.92 g cm-3 and HDPE has a density of 0.95 g cm-3. Suggest a reason why flotation is not a good method of separating these two plastics.
EASY
Diploma
IMPORTANT
Many plastic materials are disposed of by combustion. State two disadvantages of disposing of polyvinyl chloride in this way.
EASY
Diploma
IMPORTANT
Identify two difficulties and two advantages in recycling plastics.
EASY
Diploma
IMPORTANT
Nickel has a density of 8.91 g cm-3 and X-ray diffraction shows that the unit cell edge length is 0.3524 nm. Determine the packing structure for Ni.
EASY
Diploma
IMPORTANT
Draw structures representing a face centred cubic and body centred cubic unit cell.
EASY
Diploma
IMPORTANT
Sketch a graph of resistance versus temperature for a conductor and a superconductor.
MEDIUM
Diploma
IMPORTANT

Copy and complete table 3.

Element Density / g cm-3 Length of cubic crystal edge/ pm Radius of atom from X-ray diffraction data/ pm Crystal type
iron     125 BCC
sodium 0.968 429    
platinum 21.09     FCC
EASY
Diploma
IMPORTANT
What makes a group on a benzene ring either an ortho-para or a meta director?