Question Discussion & Solution

Explanation:- 

• Oxidation is a chemical reaction in which oxygen is added to a substance or hydrogen is removed from the substance. The oxidizing agent is the chemical compound that provides oxygen or removes hydrogen from the reactants. Oxidizing agents are also known as Oxidant or Oxidizer. 
• Here, Aluminium is the only metal that forms a protective layer of its own oxide Al₂O₃. This Aluminium Oxide layer serves as a barrier and prevents the element Aluminium from further corrosion.

Additional Information

•  Gold (Au):- Gold is a noble metal, it belongs to group 11 and it is least reactive. It shows +1 and +3 oxidation states.
• Silver (Ag):-  It is a white lustrous element of group 11. Being a noble metal it is less reactive in nature. Silver is a good conductor of electricity.
• Aluminum (Al):- Aluminium is a metal from group 13, It is a light-weighted silvery metal with 3+ valency. Common Oxidation states shown by Aluminium is +1, +2, +3. 
• Iron (Fe):- Iron is a highly reactive metal, It reacts with the oxygen present in the air very easily and forms Iron oxides like FeO, Fe₂O_3, Therefore, Iron undergoes rusting

 .Hint :- Au, Ag, both are  less reactive in nature, Iron is highly reactive, whereas Al is reactive in nature but doesn't react with air due to the formation of Al₂O₃ 

The pattern followed here is:

This is an alternate series of subtraction. The first number is subtracted by 2 to get the second number and then 4 is subtracted from the second number to get the third number and so on.

Hence, 42 is the correct answer.

The source of rain is clouds.

Similarly, the source of heat is fire.

The correct answer is ​Red and yellow soil.

Key Points

• Red and Yellow Soil:
  • Red soil develops on crystalline igneous rocks in areas of low rainfall in the eastern and southern part of the Deccan Plateau. Hence option 1 is correct.
  • Along the piedmont zone of the Western Ghat, a long stretch of area is occupied by red loamy soil.
  • Yellow and red soils are also found in parts of Odisha and Chhattisgarh and in the southern parts of the middle Ganga plain.
  • The soil develops a reddish colour due to a wide diffusion of iron in crystalline and metamorphic rocks.
  • It looks yellow when it occurs in a hydrated form.
  • The fine-grained red and yellow soils are normally fertile, whereas coarse-grained soils found in dry upland areas are of poor infertility.
  • They are generally poor in nitrogen, phosphorous and humus.

The correct answer is Al2O3.

Key Points

•  Al2O3  reacts with acids and bases.
  • Aluminum oxide (Al2O3) is an amphoteric substance.
  • The amphoteric substance is a substance that can react with both acids and bases usually to produce salt and water.
  • Aluminium oxide therefore can react with both acids as well as bases. We will take the example of its reaction with hydrochloric acid (strong acid) and sodium hydroxide (strong base).
  • When mixed with these two compounds aluminium oxide either acts like  acid with a base and a base with an acid.

Additional Information

• Al₂O₃ + 6 HCl → 2 AlCl₃ + 3 H₂O (acts like a base)
• Al2O3 + 2 NaOH + 3 H₂O → 2 NaAl(OH)₄ (sodium aluminate) (acts like an acid)
• On reacting Al2O3 with HCl, we get Aluminium Chloride as the salt and water as a by-product.
  • Likewise, the reaction between NaOH ( Strong Base) and Al₂O₃ results in the formation of Sodium Aluminate as salt and water.