Tag: materials: metals and non-metals

Questions Related to materials: metals and non-metals

The metallic character of elements ............. in a group from top to bottom.

  1. Increases

  2. Decreases

  3. remains constant

  4. shows indefinite behaviour


Correct Option: A

Eventhough a cinema hall is a place prone to fire hazards, the interiors are mostly made of wood or wood based panels. Why is this so ?

  1. Wood does not catch fire easily

  2. Wood is opaque

  3. Wood can absorb sound

  4. Wood is very commonly available


Correct Option: C
Explanation:

Wood is a good sound absorber. if it will be of some different material then there will be echo(a reflection of sound) in the hall and the sound will not be clear.

Most balloons, tyres and footballs are made-of rubber. This is because rubber is:

  1. naturally available

  2. cheap

  3. an electrical insulator

  4. soft and flexible


Correct Option: D
Explanation:

Prior to rubber tires, metal and wood were the materials in use. However it was found that natural Rubber provides better cushioning, makes less noise. Further rubber deforms under weight /force which results in larger contact patch with the road than with metal/wood tires of same diameter/width. During cornering at high speeds, the deformation of sidewall and larger contact area improves the traction or grip on the road increasing safety.

Generally ornaments are usually made up of 24 karat gold.

  1. True

  2. False


Correct Option: B
Explanation:

Ornaments and jewellry can't be made of 100 per cent pure gold or 24 Karat gold as it is very soft and delicate. Most of jewellry are made of 22 karat to 10 karat of gold.


24 carat is pure gold so it has less strength to make ornaments. To impart strength, some impurities are mixed such as copper to make the 22 carat gold which is suitable for making ornaments. Therefore, 24 carat gold is pure gold , it is weak to make ornaments.

Non-metals have many different colours.

  1. True

  2. False


Correct Option: A
Explanation:

Non-metals like phosphorous exist in various colors such as white, scarlet, yellow, red, violet, black. Similarly, sulfur is pale yellow, bromine is red-brown colored in liquid and vapor state.
Thus option $A$ is correct.

Non-metals are less dense and have low melting and boiling points as compared to metals.

  1. True

  2. False


Correct Option: A
Explanation:

The melting point of an element is the temperature at which it converts from solid form to a liquid. In metals, there are two types of bonding that lead to higher melting points: covalent and metallic. Covalent bonds are when electron pairs are shared equally between atoms, and they pull atoms even closer together if multiple pairs of electrons are involved. Metallic bonds involve electrons that are delocalized: they float between many atoms, not just two, and positively charged nuclei are firmly bound to the surrounding "sea" of electrons. As strong bonds between atoms give elements higher melting points, it is also true that lower melting points are a result of weaker bonds or a lack of bonds between atoms. Therefore non-metals lack metallic bonding between atoms therefore have lower melting and boiling point than metals.
Also the closed and dense packing of metals in the lattice impart them high density and strength that lacks in non-metals.
Thus option A is true.

Metals are lustrous.

  1. True

  2. False


Correct Option: A
Explanation:

Metals are lustrous because of the free electrons present in them. The free electrons can move freely in the metal causing any light incident on them to get reflected back. This reflection is specular reflection rather than diffused and thus the metal surface appears shiny or lustrous.
Hence, option $A$ is correct.