#1 The element which is used for vulcanising rubber –
Vulcanisation is a chemical process for converting rubber or related polymers into more durable materials via the addition of sulphur or other equivalent curatives or accelerators. By far the most common vulcanising methods depend on sulphur.
#2 Which one of the following is used in making pencils?
Graphite is used to make pencil.
#3 Pollutant from motor car exhaust that causes mental disease is –
Pollutant from motor car exhaust that causes mental disease is lead. Lead is produced cause lead poisoning.
#4 Ozone layer is present in –
Ozone layer is present in Stratosphere.
#5 The two metal ions that cause hardness to water are –
The bicarbonates, chlorides and sulphates of calcium and magnesium cause hardness to water.
The bicarbonates cause temporary hardness while chlorides and sulphates cause permanent hardness.