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Multiple choice chemistry non-metals introduction to non-metals occurence of metals occurrence of metals and non metals

Minerals that have a relatively high concentration of metal and can be extracted in an easy and cost-effective process are called:

  1. Metalloids

  2. Gold crust

  3. Ores

  4. None of above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Minerals that have a relatively high concentration of metal and can be extracted in an easy and cost-effective process are called ores.

Multiple choice chemistry non-metals introduction to non-metals occurence of metals occurrence of metals and non metals

Which of the following are found in Earth's crust mainly as oxides, sulphides and carbonates?

  1. Metals above in the activity series

  2. Metals in the middle of the activity series

  3. Metals at the bottom of the activity series

  4. All of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The metals at the bottom of the activity series are the least reactive. They are often found in a free state. For example, gold, silver, platinum and copper are found in the free state. Copper and silver are also found in the combined state as their sulphide or oxide ores. The metals at the top of the activity series $(K, Na, Ca, Mg$ and $Al)$ are so reactive that they are never found in nature as free elements. The metals in the middle of the activity series $ (Zn, Fe, Pb, etc.)$ are moderately reactive. They are found in the earth’s crust mainly as oxides, sulphides or carbonates. The ores of many metals are oxides. This is because oxygen is a very reactive element and is very abundant on the earth.

Multiple choice chemistry non-metals introduction to non-metals occurence of metals occurrence of metals and non metals

Blister copper is:

  1. pure copper

  2. ore of copper

  3. alloy of copper

  4. impure copper
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Blister copper is an impure form of copper having a blister-like surface due to the release of gas during cooling. The purity of this product is 98%, it is known as blister because of the broken surface created by the escape of sulfur dioxide gas as blister copper pigs or ingots are cooled.
Multiple choice chemistry non-metals introduction to non-metals occurence of metals occurrence of metals and non metals

Silver can be separated from lead by:

  1. fractional crystallization

  2. amalgamation

  3. cupellation

  4. addition of zinc
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The Parkes process is a pyrometallurgical industrial process for removing silver from lead during the production of bullion. It is an example of liquid–liquid extraction.
The process takes advantage of two liquid-state properties of zinc. The first is that zinc is immiscible with lead, and the other is that silver is 3000 times more soluble in zinc than it is in lead. When zinc is added to liquid lead that contains silver as a contaminant, the silver preferentially migrates into the zinc. Because the zinc is immiscible in the lead it remains in a separate layer and is easily removed. 
Multiple choice chemistry non-metals introduction to non-metals occurence of metals occurrence of metals and non metals

Statement: Valuable gemstones such as rubies and sapphire contain aluminium oxides along with traces of transition metals as impurities.


State whether the given statement is true or false.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sapphire is a gemstone, a variety of the mineral corundum, an aluminium oxide. It is typically blue, but natural "fancy" sapphires also occur in yellow, purple, orange, and green colours.


The only colour which sapphire cannot be is red – as red-coloured corundum is called ruby. Rubies are crystalline forms of aluminium oxide, which are red due to the presence of chromium as an impurity.

A rare variety of natural sapphire, known as colour-change sapphire, exhibits different colours in a different light.

The colour-change effect is caused by the interaction of the sapphire, which absorbs specific wavelengths of light, and the light source, whose spectral output varies depending upon the illuminant.
Transition-metal impurities in the sapphire, such as chromium and vanadium, are responsible for the colour change.

Hence, the given statement is $\text{true}$

Multiple choice chemistry non-metals introduction to non-metals occurence of metals occurrence of metals and non metals

Aluminium metal is purified by:

  1. Hoopes process

  2. Halls process

  3. Serpecks process

  4. Baeyers process
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

All processes are used in Aluminium metallurgy but the Hoopes process is a metallurgical process, used to obtain the aluminium metal of very high purity.
The Bayer process is the principal industrial means of refining bauxite to produce alumina (aluminium oxide).
The Hall–Héroult process is the major industrial process for smelting aluminium. 
Serpeck's process  is used for the purification of bauxite ore containing silica  as the main impurity