Chemical Bonding - 1

Chemical Bonding - 1

1. An ionic bond can be formed between two atoms when

one of them has a low ionization energy and the other a high electron affinity
both the atoms have high values of ionization energy
both the atoms have low values of electron affinity
both the atoms have low values of ionization

2. The cohesive energy of an ionic crystal is the energy

liberated during its formation from individual neutral atoms
liberated during the formation of positive ions
absorbed during its formation from individual neutral atoms
absorbed during the formation of negative ions

3. An ionic solid is a poor conductor of electricity because

ions have uniform fields of influence
ions do not conduct electricity
the charge on the ions is uniformly distributed
ions occupy fixed positions in solids

4. A covalent bond is formed between two atoms when

the two atoms are of the same size
the electron affinities of the two atoms are the same
one or more pairs of electrons are shared by the two atoms
the electronegativities of the two atoms differ considerably

5. Which of the following is required for the formation of an ionic bond?

The total energy of the resulting molecule should be less than the total energy of the reactants
The ionic potentials of the reactants should be identical
An electron from the more electronegative element should be transferred to the less electronegative element
The lattice energy of the resultant molecule should be as low as possible

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Aircraft nomenclature

Roll over the hotspots for details

 

 

 

 

 

 

 

 

 

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NACA Series

NACA Series

1. In a NACA 4 digit series, what does the first number represent?

Maximum thickness as percentage of chord
Minimum camber as percentage of chord
Maximum camber as percentage of chord
Minimum thickness as percentage of chord

2. Default maximum thickness of a 4 digit NACA series aerofoil is?

30% of the chord from leading edge
45% of chord from leading edge
15% of chord from leading edge
25% of chord from leading edge

3. What is the maximum camber location of a NACA 2412 aerofoil from leading edge?

0.8
0.2
0.12
0.4

4. What is the theoretical optimum lift coefficient of a NACA 23112 aerofoil at ideal angle of attack?

0.2
0.15
0.3
0.45

5. What does the third digit in a NACA 5 series aerofoil represent?

Camber is simple or reflex
Maximum Lift coefficient
15% of chord from leading edge
Maximum thickness of aerofoil

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