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Chemistry

55 questions in Science & Technology.

Asked in 2002, 2001, 2000, 1999, 1998, 1997

2002 · Q28Science & TechnologyChemistrymoderate

Which one of the following statements is correct?

  1. (a)The boiling point of an aqueous solution is higher than that of pure water
  2. (b)Addition of solutes to a solution causes an increase in its water potential
  3. (c)The vapour pressure of the water in a solution is lower than that of pure water
  4. (d)When a solution is separated from water by a semi permeable membrane, water movement can be prevented by applying pressure to the solution
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Official answer(b) Addition of solutes to a solution causes an increase in its water potential

2002 · Q110Science & TechnologyChemistrydifficult

Match List I (Oxidation number) with List II (The element) and select the correct answer using the codes given below the lists: List I (Oxidation number) — List II (The element) A. 2 — 1. Oxidation number of Mn in MnO₂ B. 3 — 2. Oxidation number of S in H₂S₂O₇ C. 4 — 3. Oxidation number of Ca in CaO₂ D. 6 — 4. Oxidation number of Al in NaAlH₄

  1. (a)A-3, B-4, C-1, D-2
  2. (b)A-4, B-3, C-1, D-2
  3. (c)A-3, B-4, C-2, D-1
  4. (d)A-4, B-3, C-2, D-1
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Official answer(a) A-3, B-4, C-1, D-2

2002 · Q145Science & TechnologyChemistrymoderate

Assertion (A): Synthetic detergents can lather well in hard water. Reason (R): Synthetic detergents form soluble calcium and magnesium salts with hard water.

  1. (a)Both A and R are individually true and R is the correct explanation of A
  2. (b)Both A and R are individually true but R is not a correct explanation of A
  3. (c)A is true but R is false
  4. (d)A is false but R is true
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Official answer(a) Both A and R are individually true and R is the correct explanation of A

2001 · Q116Science & TechnologyChemistryeasy

Assertion (A): A chemical reaction becomes faster at higher temperatures. Reason (R): At higher temperatures, molecular motion becomes more rapid. Which of the following is correct?

  1. (a)Both A and R are individually true and R is the correct explanation of A
  2. (b)Both A and R are individually true but R is NOT a correct explanation of A
  3. (c)A is true but R is false
  4. (d)A is false but R is true
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Official answer(a) Both A and R are individually true and R is the correct explanation of A

2001 · Q121Science & TechnologyChemistrymoderate

Consider the following statements with reference to the Periodic Table of chemical elements: I. Ionisation potential gradually decreases along a period. II. In a group of elements, electron affinity decreases as the atomic weight increases. III. In a given period, electronegativity decreases as the atomic number increases. Which of these statement(s) is/are correct?

  1. (a)I only
  2. (b)II only
  3. (c)I and III
  4. (d)II and III
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Official answer(b) II only