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1
Which one of the following metals is less reactive than hydrogen?
» Explain it
B
In the reactivity series of metals, copper is placed below the hydrogen hence, it is less reactive than hydrogen. On the other hand barium, lead and magnesium are placed above the hydrogen hence, these are more reactive than hydrogen.

The metals coppersilvergold and platinum are less reactive than hydrogen because they do not replace hydrogen from water or acid.

Examples for metal-displacement reactions: Zinc can displace copper from copper sulphate solution and iron from ferrous sulphate solution. So zinc is more reactive than iron and copper.
2
Which one of the following substances is made from natural raw materials?
» Explain it
A
Rayon is a textile, made from natural raw materials like cellulose. These are of two types, both made from wood pulp. Rayon is also called artificial silk.
» Explain it
A
An a-particle is identical with helium nuclei. It consists of 2 protons and 2 neutrons and represented by 2He4.
4
Which of the following isotopes of carbon is/are used in carbon dating?
» Explain it
C
The isotope of carbon 6C14 is used in radio carbon dating.

Chemistry
» Explain it
A
Reverse osmosis method is used to obtain pure water from water containing a salt or for desalination of sea water.
 
Chemistry