-
Refer to the table, answer questions 7-9.
Table: Some properties of elements at 25C and 1 atm pressure
Hardness or
Appearance
Electricity
conductivity
Element
Melting
Boling
point (C)
toughness
point (C)
Shiny, silvery liquid
Mercury
Yes
-39
357
Colourless gas
Hydrogen
No
-259
-253
Iron
Shiny, silvery solid
Hard and tough
Yes
1,538
2,861
Sulphur
Yellow solid
Hard and brittle
No
120
445
Sodium
Shiny, silvery solid
Soft and tough
Yes
98
883
Silicon
Shiny, silvery solid
Hard and brittle
Slightly
1,414
3,265
Boron
Black Solid
Hard and brittle
No
2,030
3,900
Chlorine
Yellowish green gas
No
- 102
-35
Bromine
Orange red liquid
No
-7
59
Oxygen
Colourless gas
No
-219
- 183
Magnesium
Shiny, silvery solid
Hard and tough
Yes
650
1,090
lodine
Shiny, dark purple
Hard and brittle
No
113.5
184.5
Solid
7.
Which elements are metals and which are non-metals?
8.
Is silicon a metal or non-metal or metallloid? Justify your reason.
9.
What are the uses of metals, non-metals and metalloids in daily life? Give examples.
0. Blement A is a solid with shiny ธurfaces, good electricity and heat conductivity, the density
Or 7.8 g/cm, boiling point of 1,090 C and melting point of 650 C. Is Element A a metal or
non-metal? Justify your reasons.
67