Tag: metals

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Questions Related to metals

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

Rancidity of fats can be prevented by antioxidants.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
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.
Multiple choice chemistry metals effects of oxidation reactions in daily life corrosion of metals electroplating and its application

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

  1. (i) and (ii)

  2. (ii) and (iii)

  3. (i) and (iv)

  4. (iii) and (iv)
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

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

  1. endothermic

  2. exothermic

  3. Synthesis

  4. Combination
Reveal answer Fill a bubble to check yourself
A Correct answer
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. 

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

Rancidity can be prevented by -

  1. adding anti-oxidants

  2. packing oily food in nitrogen gas

  3. packing oily food in argon gas

  4. use of spices
Reveal answer Fill a bubble to check yourself
A,B,D Correct answer
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.

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

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

  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
Reveal answer Fill a bubble to check yourself
D Correct answer
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.