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General ScienceMediumAsked in: NDA · 21 April 2024

Of the following, which does not belong to a nuclear reactor?

  1. A.A turbine
  2. B.A heat exchanger
  3. C.A mechanism to reduce CO2 emission
  4. D.A reaction chamber

Correct answer

C. A mechanism to reduce CO2 emission

Explanation

The correct answer is C, a mechanism to reduce CO2 emission. A nuclear reactor splits heavy atoms; it burns no fuel, so it releases no carbon dioxide and needs no equipment to cut such emissions. The heat of fission is produced in the reactor core, carried away by a coolant, passed to water in a heat exchanger or steam generator, and the steam then turns a turbine coupled to a generator. Control rods of cadmium or boron absorb spare neutrons and a moderator such as heavy water slows them down so that fission continues steadily. Option A is wrong as a choice because the turbine is the part that actually converts steam energy into electricity. Option B is wrong because the heat exchanger carries heat from the radioactive coolant loop to the clean water loop. Option D is wrong because the reaction chamber, the core holding the fuel rods, is where fission happens. Exam tip: a nuclear plant emits no carbon dioxide; its waste problem is spent radioactive fuel instead.

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Q2.General ScienceAsked in: CDS · CDS-I 2019, GKEasy

Which one of the following statements is correct?

  1. A.Urea is produced in liver.
  2. B.Urea is produced in blood.
  3. C.Urea is produced from digestion of starch.
  4. D.Urea is produced in lung and kidney.
Show answer
Correct answer: A. Urea is produced in liver.

Liver cells turn the toxic ammonia released from the breakdown of amino acids into urea through the ornithine cycle, also called the urea cycle.

Q3.General ScienceAsked in: CDS · CDS-I 2019, GKMedium

Which one of the following is the correct sequence of passage of light in a compound microscope?

  1. A.Condenser-Objective lens-Eyepiece-Body tube
  2. B.Objective lens-Condenser-Body tube-Eyepiece
  3. C.Condenser-Objective lens-Body tube-Eyepiece
  4. D.Eyepiece-Objective lens-Body tube-Mirror
Show answer
Correct answer: C. Condenser-Objective lens-Body tube-Eyepiece

Light passes through the condenser to the specimen, is picked up by the objective lens, travels up the body tube and reaches the eye through the eyepiece.

Q4.General ScienceAsked in: CDS · CDS-I 2019, GKEasy

Which one of the following statements regarding haemoglobin is correct?

  1. A.Haemoglobin present in RBC can carry only oxygen but not carbon dioxide.
  2. B.Haemoglobin of RBC can carry both oxygen and carbon dioxide.
  3. C.Haemoglobin of RBC can carry only carbon dioxide.
  4. D.Haemoglobin is only used for blood clotting and not for carrying gases.
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Correct answer: B. Haemoglobin of RBC can carry both oxygen and carbon dioxide.

It binds oxygen at its iron-containing haem groups and carries some carbon dioxide on its protein chains. Each haemoglobin molecule has four polypeptide chains and four haem groups, and each haem iron can hold one oxygen molecule, forming oxyhaemoglobin in the lungs.

Q5.General ScienceAsked in: CDS · CDS-I 2019, GKEasy

Which one of the following statements regarding histone proteins is correct?

  1. A.Histones are proteins that are present in mitochondrial membrane.
  2. B.Histones are proteins that are present in nucleus in association with DNA.
  3. C.Histones are proteins associated with lipids in the cytosol.
  4. D.Histones are proteins associated with carbohydrates in the cytosol.
Show answer
Correct answer: B. Histones are proteins that are present in nucleus in association with DNA.

They are the proteins around which DNA winds to form chromatin in the nucleus of eukaryotic cells. Histones are small basic proteins, rich in the positively charged amino acids lysine and arginine, which attract the negatively charged phosphate groups of DNA.