250+ TOP MCQs on Towards Quantum Mechanical Model of the Atom and Answers

Chemistry Objective Questions & Answers on “Towards Quantum Mechanical Model of the Atom”.

1. Who found out about dual behavior of a matter?
a) De Broglie
b) Bohr
c) Rutherford
d) Thomson
Answer: a
Clarification: A French physicist named Louis de Broglie proposed that matter exhibits both particle and wave like nature. This means that like photons, electrons also should have both momentum and wavelength.

2. A ball of mass 0.5kg is moving with velocity 6.626 m/s. What’s the wavelength of that ball?
a) 1 x 10-34 m
b) 2 x 10-34 m
c) 2 x 10-32 m
d) 2 x 10-3 m
Answer: b
Clarification: Louis de Brogie gave the realation between momentum and wavelength as λ = h/p. Here h is Planck’s constant, whose value is 6.626 x 10-34 J/s. Wavelength = h/mv = 2 x 10-34 m (momentum p = mass m x velocity v).

3. Mass of a photon is given by 3.313 x 10-34 kg. Find it’s wavelength.
a) 0.67A°
b) 0.67nm
c) 0.37A°
d) 1.67A°
Answer: a
Clarification: Louis de Brogie gave the realation between momentum and wavelength as λ = h/p. Here h is Planck’s constant, whose value is 6.626 x 10-34 J/s. Wavelength = h/mc = 6.626 x 10-34 Js/(3.313 x 10-34 kg x 3 x 108 m/s) = 0.67A°.

4. Determining the exact position and velocity of an electron is impossible at a time.
a) True
b) False
Answer: a
Clarification: A German physicist, Werner Heisenberg stated Heisenberg’s principle of uncertainty, that states that determining the exact position and velocity of an electron is impossible at a time, as a result of dual nature of matter and radiation.

5. As per Heisenberg’s principle of uncertainty, the relation between relative momentum and relative position is __________
a) independent
b) equal
c) directly proportional
d) inversely proportional
Answer: d
Clarification: Heisenberg’s principle of uncertainty states that the product of relative momentum and velocities is equal to greater than the h/4π, where is “h” is the Planck’s constant and is equal to 6.626 x 10-34 Js.

6. The uncertainty of a ball is given by 0.5A°. Then calculate the uncertainty in momentum.
a) 2.055 x 10-24 kgm/s
b) 1.015 x 10-24 kgm/s
c) 1.055 x 10-24 kgm/s
d) 1.095 x 10-24 kgm/s
Answer: c
Clarification: Heisenberg’s principle of uncertainty states that Δx. Δp ≥ h/4π, x is position, p is momentum and “h” is the Planck’s constant and is equal to 6.626 x 10-34 Js. Relative momentum Δp = h/4πΔx = 1.055 x 10-24 kgm/s.

7. If the uncertainties in position and momentum are equal, then the uncertainty in position is given by ____
a) √h/4π
b) √h4π
c) √h/4
d) √h/π
Answer: a
Clarification: As we know, Heisenberg’s principle of uncertainty states that Δx. Δp ≥ h/4π, x is position, p is momentum and “h” is the Planck’s constant. Δx = Δp; Δx. Δx = h/4π; Δx = √h/4π

8. If the kinetic energy of an electron is 5J. Find out its wavelength.
a) 0.313 x 1015 m/s
b) 3.013 x 1015 m/s
c) 3.310 x 1015 m/s
d) 3.313 x 1015 m/s
Answer: d
Clarification: We know that the mass of an electron is 9.1 x 10-31 kg. Given that the kinetic energy of an electron is 5J. K.E = mv2/2 and by substituting we get v = √1.098 x 1031 m/s = 3.313 x 1015m/s.

9. An object has a mass of 6 kg and velocity of 10 m/s. The speed is measured with 5% accuracy, then find out Δx in m.
a) 0.12676 x 10-34
b) 0.1566 x 10-34
c) 0.176 x 10-34
d) 0.276 x 10-34
Answer: c
Clarification: Speed’s uncertainty is 10 x 5/100 = 0.5 m/s. We have Heisenberg’s principle of uncertainty i.e. Δx. Δp ≥ h/4π. Δx = h/2mπ. Therefore uncertainty in position = 6.626 x 10-34 Js/12 x 3.1416 = 0.176 x 10-34.

10. Δx. Δp ≥ h/4π.
a) True
b) False
Answer: a
Clarification: Heisenberg’s principle of uncertainty states that the product of relative momentum and velocities is equal to greater than the h/4π, where is “h” is the Planck’s constant and is equal to 6.626 x 10-34 Js. Hence the above statement is true.

250+ TOP MCQs on Hydrogen Bonding and Answers

Chemistry Multiple Choice Questions on “Hydrogen Bonding”.

1. Nitrogen, fluorine and oxygen are ___________ in nature.
a) electronegative
b) electropositive
c) metallic
d) semi-metallic
Answer: a
Clarification: Electronegativity is the tendency of a neutrally isolated gaseous atom to attract an electron. This is high in the case of nitrogen, oxygen, and fluorine. So the negative charge in the hydrogen bond is towards them.

2. Which bond acts like a bridge two molecules formed by a covalent bond?
a) Covalent bond
b) Ionic bond
c) Hydrogen bond
d) Metallic bond
Answer: c
Clarification: For example, consider a molecule that’s formed due to a covalent between hydrogen and fluorine. Here hydrogen acquires a positive charge. Hydrogen bond formation occurs between hydrogen in a molecule and fluorine of the other molecule.

3. A molecule named o-nitrophenol consists of ______________hydrogen bond/s.
a) intermolecular
b) intramolecular
c) both intermolecular and intramolecular
d) neither intermolecular nor intramolecular
Answer: b
Clarification: The presence of hydrogen between molecules is intermolecular hydrogen bond and presence of hydrogen bond in the molecule itself is intramolecular hydrogen bond. In o-nitrophenol, there is a hydrogen bond between the hydrogen of the hydroxide group and oxygen.

4. In a hydrogen bond, hydrogen has a positive charge.
a) True
b) False
Answer: a
Clarification: IN the hydrogen bond, the other element is highly electronegative, So the hydrogen becomes electropositive comparatively in this case and there is a displacement of electrons towards the electronegative side. Hence hydrogen has a positive charge.

5. Water molecules contain _____________ hydrogen bond/s.
a) intermolecular
b) intramolecular
c) both intermolecular and intramolecular
d) neither intermolecular nor intramolecular
Answer: a
Clarification: In a water molecule, the hydrogen bonds are formed between other molecules but not within the same molecule. The presence of hydrogen between molecules is intermolecular hydrogen bond and presence of hydrogen bond in the molecule itself is intramolecular hydrogen bond.

6. The magnitude of the H-bonding depends on the ___________ of the compound.
a) surroundings
b) system
c) atmosphere
d) physical state
Answer: d
Clarification: The magnitude of the H-bonding depends on the physical state of the compound. In the gaseous state, it is minimum and in the solid state, it is maximum. There is a great influence on a compound’s structure and properties.

7. Which of the following molecule can form a hydrogen bond with hydrogen?
a) Sodium
b) Oxygen
c) Aluminum
d) Rubidium
Answer: b
Clarification: Most Electronegative elements can only form hydrogen bonds with hydrogen, Among Sodium, Oxygen, Aluminium, and Rubidium, Oxygen is the electronegative element. So only oxygen can form a hydrogen bond.

8. Which of the following molecules doesn’t involve hydrogen bond formation?
a) H2O
b) O-nitrophenol
c) NaCl
d) HF
Answer: c
Clarification: Water, Hydrogen fluoride include intermolecular hydrogen while o-nitrophenol has intramolecular hydrogen bonding. Sodium Chloride NaCl has an ionic bond that is much stronger than hydrogen bond.

9. In a hydrogen bond, the electron pair that is shared moves away from hydrogen.
a) True
b) False
Answer: a
Clarification: Yes, in the formation of a hydrogen bond, the electron pair moves away from hydrogen. This occurs due to the high electronegativity of other atoms participating in a hydrogen bond. So naturally, hydrogen has positive charges and electrons move away.

10. Alcohol and HF molecule contains __________ & _____________ hydrogen bonds.
a) intramolecular, intermolecular
b) intermolecular, intermolecular
c) intermolecular, intramolecular
d) intramolecular, intramolecular
Answer: b
Clarification: The presence of hydrogen between molecules is intermolecular hydrogen bond and the presence of hydrogen bond in the molecule itself is intramolecular hydrogen bond. So it’s intermolecular in case of alcohol and water.