Chemistry Practice Test 6


Question 1

In dehydrohalogenation, which of the following is used to remove hydrogen from alkyl halide?

  1. Base
  2. Acid
  3. Leaving group
  4. Double bond
  5. Solvent

Correct Answer : a) Base

Explanation:

In dehydrohalogenation, a strong base is required to remove hydrogen from alkyl halide and thus it forms alkene as a product. It is also known as ß-elimination reaction.

Question 2

25. A crystal plane has intercepts of a, b/2 and 3c/2 along the X, Y and Z axes respectively. What are its Millar indices?

  1. (1 1/2 3/2)
  2. (123)
  3. (122/3)
  4. (362)
  5. (243)

Correct Answer : d) (362)

Explanation:

Miller indices are a set of integers (h, k, and l), which are used to describe a given plane in a crystal. The procedure for determining the Miller indices for a plane:
1. Take the intercepts of the plane (a, b, c) with these axes.
2. Invert all the numbers.
3. Clear fractions to obtain h, k and l
For the above plane, the miller indices can be calculated as follows
The plane: a, b/2, 3c/2
Intercepts: 1, 1/2, 3/2
Reciprocals: 1, 2, 2/3
Clear fractions: 3, 6, 2
Hence, the Miller indices are (362)

Question 3

The energy band diagram corresponds to

  1. I-Conductor, II-Insulator
  2. I-Semiconductor, II-Insulator
  3. I-Insulator, II-Conductor
  4. I-Insulator, II-Semiconductor
  5. I-Conductor, II-Semiconductor

Correct Answer : d) I-Insulator, II-Semiconductor

Explanation:

The energy band diagram I corresponds to an insulator in which the energy gap is very high. The diagram II corresponds to a semiconductor in which the energy gap is small compared to that of an insulator.

Question 4

The respiration process of human beings is based on the principle of

  1. Boyle's law
  2. Charles law
  3. Dalton's law of partial pressure
  4. Graham's law
  5. Both a)&b)

Correct Answer : a) Boyle's law

Explanation:

During inhalation of gas, pressure inside the lung drops below the air pressure decreases and the chest cavity expands and thus volume gets increased. This shows that pressure and volume are inversely related to each other.

Question 5

In the given reaction, which element gets oxidised?
I2 + H2 S → H+ + I- + S(s)

  1. I
  2. S
  3. H
  4. I and S
  5. S and H

Correct Answer : b) S

Explanation:

The oxidation state of Iodine goes from 0 in I2to -1 in I-. The oxidation state of sulphur goes from -2 in H2S to 0 in S(s). So, Iodine gets reduced and sulphur gets oxidised.

Question 6

Based on the first law of thermodynamics, which of the following is correct?

  1. For an isothermal process, q = +w
  2. For an isochoric process, ΔU = -q
  3. For an adiabatic process, ΔU = -w
  4. For a cyclic process, q = -w
  5. None of these

Correct Answer : d) For a cyclic process, q = -w

Explanation:

For the first law of thermodynamics, cyclic process q = -w. For an isothermal process, w = -q. For an adiabatic process, ΔU = w, since q = 0.

Question 7

The quantum number which describes the shape of the orbital is

  1. Principal quantum number
  2. Azimuthal quantum number
  3. Magnetic quantum number
  4. Angular quantum number
  5. Both b and d

Correct Answer : e) Both b and d

Explanation:

Azimuthal or angular quantum number describes the shapes of the orbital. Principal quantum number describes the size and energy of the orbital. Magnetic quantum number describes the orientation in space of a particular orbital.

Question 8

Representative elements are those which belong to

  1. s& d-block elements
  2. p& d-block elements
  3. s& p-block elements
  4. d& f-block elements
  5. s& f-block elements

Correct Answer : c) s & p-block elements

Explanation:

The p-block elements comprise those belonging to groups 13 to 18 and together with the s-block elements are called Representative Elements.

Question 9

The conversion of methane to chloromethane in the presence of UV light is an example for

  1. Electrophilic addition
  2. Elimination
  3. Nucleophilic substitution
  4. Free radical substitution
  5. Photochemical free radical reaction

Correct Answer : e) Photochemical free radical reaction

Explanation:

Free radical reactions are of two types, photochemical fission and thermal fission. The reaction, which takes place in presence of UV light is called photochemical fission reaction.

Question 10

Amixture of nitrobenzene and benzene can be separated by using

  1. Simple distillation
  2. Fractional distillation
  3. Steam distillation
  4. Filtration
  5. Crystallisation

Correct Answer : simple distillation

Explanation:

The liquids with boiling points widely apart (about 40K and above) can be purified by simple distillation, if they do not decompose under ordinary pressure. Nitrobenzene has a boiling point of 484K and benzene has a boiling point of 354K. So, it they can be separated using simple distillation.

Question 11

Basic principle of crystallization is that solute should be soluble in a suitable solution at

  1. Low temperature
  2. High temperature
  3. Room temperature
  4. Freezing temperature
  5. Either a or b

Correct Answer : b) High temperature

Explanation:

The solvent should be added little by little with constant stirring and heating till all the solute particles get dissolved in a solvent. Then filtration process has to be carried, followed by crystallization process.

Question 12

Pick out the correct phrase(s) about the acidity of compounds.
I. Weaker the acid, smaller the value of Ka.
II. Stronger the acid, lesser the value of degree of hydrolysis
III. Kh = Ka / Kw

  1. I and II
  2. I and III
  3. I only
  4. I,II and III
  5. II and III

Correct Answer : a) I and II

Explanation:

The weaker the acid, the smaller is the value of Ka and greater the degree of hydrolysis. The hydrolysis constant Kh of the salt varies inversely as the dissociation constant Ka of the weak acid.

Question 13

When 4g of glucose is dissolved in 250mL of hot water, its molarity will be

  1. 0.88 M
  2. 0.088 M
  3. 11.363 M
  4. 8.8 M
  5. 5.8 M

Correct Answer : b) 0.088 M

Explanation:

Molecular weight of glucose is 180 M
Number of moles of glucose in 4g is 4 g/180 g mol = 0.022 mol.
Convert the volume of solvent in litres 250 mL*(1 L/1000 mL) = 0.2501 L
Molarity = Mass/volume = 0.022 mol/0.2501 L = 0.088 mol/L or 0.088 M.

Question 14

Example for monoclinic crystal structure is

  1. Rutile
  2. Rock salt
  3. Silica
  4. Gypsum
  5. Calcite

Correct Answer : d) Gypsum

Explanation:

Gypsum – monoclinic crystal structure, rutile – tetragonal, rock salt – cubic structure, silica – hexagonal, calcite – rhombohedral.

Question 15

CO2 filled in soft drinks is an example for

  1. Dalton's law
  2. Raoult's law
  3. Henry's law
  4. Colligative property
  5. None of these

Correct Answer : c) Henry's law

Explanation:

Henry's law states that the solubility of a gas in a liquid is directly proportional to the pressure of the gas.








































































































































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