Tag: electroplating and its application

Questions Related to electroplating and its application

Rancidity of fats can be prevented by antioxidants.

chemistry metals effects of oxidation reactions in daily life corrosion of metals electroplating and its application

  1. True

  2. False

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Correct Option: A
Explanation:
Rancidity- it is the complete or incomplete oxidation or hydrolysis of fats and oils when exposed to air, light, moisture or by bacterial action, resulting in unpleasant taste and odour.
Rancidity can be prevented by:-
  • Storing foods away from light, In the absence of light the oxidation process of fats and oils slows down and thus rancidity is retarded. 
  • Adding antioxidants to foods containing fats and oils.

Solid calcium oxide reacts vigorously with water to form calcium hydroxide accompanied by liberation of heat. This process is called slaking of lime. Which among the following is (are) true about slaking of lime?
(i) It is an endothermic reaction
(ii) It is an exothermic reaction
(iii) The pH of the resulting solution will be more than seven
(iv) The pH of the resulting solution will be less than seven

chemistry metals effects of oxidation reactions in daily life corrosion of metals electroplating and its application

  1. (i) and (ii)

  2. (ii) and (iii)

  3. (i) and (iv)

  4. (iii) and (iv)

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Correct Option: B
Explanation:

Slaking, the process of turning the traditional building material lime from calcium oxide (burnt lime or quicklime) into calcium hydroxide (slaked lime, slack lime, limewater, pickling lime or hydrated lime).
Its exothermic process and as calcium hydroxide is basic so pH will be greater than 7.

Reactions in which energy is absorbed are known as........... reactions.

chemistry metals effects of oxidation reactions in daily life corrosion of metals electroplating and its application

  1. endothermic

  2. exothermic

  3. Synthesis

  4. Combination

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Correct Option: A
Explanation:

Endothermic reactions:
These are reactions that take in energy from the surroundings. The energy is usually transferred as heat energy, causing the reaction mixture and its surroundings to get colder. The temperature decrease can also be detected using a thermometer. 

Rancidity can be prevented by -

chemistry metals effects of oxidation reactions in daily life corrosion of metals electroplating and its application

  1. adding anti-oxidants

  2. packing oily food in nitrogen gas

  3. packing oily food in argon gas

  4. use of spices

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Correct Option: A,B,D
Explanation:

Rancidity is decomposition of oils, fats and lipids. It normally happens when food items are stored for a long time and gets exposed to oxygen.. Rancidity can be prevented by adding anti-oxidants, vacuum packing, replacing air by nitrogen, refrigeration of the food-stuff or packaging of food items in airtight containers.

Which step(s) in glycolysis require the input of energy?

chemistry metals effects of oxidation reactions in daily life corrosion of metals electroplating and its application

  1. The glucose priming step

  2. The phosphorylation of glucose

  3. The phosphorylation of fructose 6-phosphate

  4. All of these steps require the input of energy

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Correct Option: D
Explanation:

There are two phases of glycolysis. Priming phase because it requires an input of energy in form of 2 ATPs per glucose molecule and the pay off phase because energy is released in the form of 4 ATPs. The phosphorylation of glucose uses ATP mas the source of phosphate and produce glucose$-6-$phosphate. The second ATP is used in phosphorylation of fructose$-6-$phosphate to fructose$-6-$bisphosphate. All of the given steps requires the input of energy.

In electrochemical passivity:

chemistry changes - physical and chemical effects of oxidation reactions in daily life corrosion of metals electroplating and its application

  1. thin visible oxide film is formed

  2. thin invisible oxide film is formed

  3. thick visible oxide film is formed

  4. thick invisible oxide films formed

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Correct Option: B
Explanation:

During electrochemical passivisation, the metal surface is made inactive by formation of thin invisible oxide layer on the surface. 


This is done by the oxidation of metal on metal surface.

Hence, option B is correct.

Any article of iron if left in open for some time, acquires a film of brownish substance (rust) having chemical formula:

chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

  1. $Fe _3O _4$

  2. $Fe _2O _3$

  3. FeO

  4. $Fe(OH) _2$

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Correct Option: B
Explanation:

Iron reacts with air to form iron oxide(III) which is known by the name rust or rusting of iron. Rust is an iron oxide or red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture. Rust consist of hydrated iron oxide.

Rusting of iron takes place only when both ...................... and ...................... are present.

chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

  1. Air, moisture

  2. Oil, sand

  3. Sand, water

  4. None of the above

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Correct Option: A
Explanation:

Rusting of iron takes place only when both air and moisture are present.

Why corrosion is more seen in damp areas?

chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

  1. Damp areas are deficient of light

  2. Damp areas provides air and water

  3. Both $A$ and $B$

  4. None of the above

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Correct Option: B
Explanation:

Damp areas alone supplies both the things air and water required for the rusting of iron.

Corrosion occurs due to:
a) action of water on the metal.
b) action of air on the metal.
c) action of temperature on the metal.

chemistry changes around us effects of oxidation reactions in daily life corrosion of metals electroplating and its application

  1. a, b

  2. b, c

  3. a, c

  4. all of the above

Show answer
Correct Option: A
Explanation:

An action of air and water gradually eats up the metal. This eating up of metals by the action of air and moisture on their surface is called corrosion.