Which of the following is the hardest metal?

SOLUTION

Concept:

• Hardness of the mineral is defined on the Moh's scale of hardness. In this scale, a mineral is rated in between 1-10 on the basis of their strength.
• It is used to rate the hardness of a variety of substances and elements, not only metals. The softest materials it rates are assigned a rating of 1; the hardest earn a rating of 10.​ 

Explanation:

The Moh's scale of different minerals shown below -

• Tungsten is the hardest metal. ∴ Option 4 is correct.
• Platinum is less harder metal. That's why it is used in Jewellery. It can make intricate designs. It is highly ductile.
• The name Tungsten originates from the Swedish name tungsten meaning heavy stone.
• Hardness is the ability to scratch making a dent on the surface of the metal. It is just a number measured using (Rockwell, Brinell, Vickers test)  Of which Brinell is most accurate.
• Gold: 25 Mpa
• Platinum: 40 Mpa
• Tungsten: 310 Mpa
• Iron: 150  Mpa
• Diamond: 10000  Mpa(Non-metal)
• It is a chemical element with atomic number 74 has the highest tensile strength of all the metals present in the world. Its symbol is  "W"