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'A' Level Atomic Structure

Multiple Choice Questions

Q1. An atom of gains 3 electrons.

What is the specific charge of the ion?

A
1.80 × 107 C kg–1
B
- 1.80 × 107 C kg–1
C
4.19 × 107 C kg–1
D
−4.19 × 107 C kg-1

 

specific charge = Q/m

charge on the ion = -3e

Q = -3 x 1.60 x 10-19 C

Q = - 4.80 x 10-19 C

mass of the ion = 16 x 1.67 x 10-27 kg

m = 2.67 x 10-26 kg

specific charge = - 4.8 x 10-19/2.67 x 10-26

= - 1.8 x 107 C/kg (Choice B)

Q2. Fluoride ions are produced by the addition of a single electron to an atom of fluorine .

What is the magnitude of specific charge of the fluoride ion?

A
3.2 × 10−26 C kg–1
B
8.4 × 10−21 C kg–1
C
5.0 × 106 C kg–1
D
4.5 × 107 C kg-1

specific charge = Q/m

charge on the ion = -e

Q = -1.60 x 10-19 C

mass of the ion = 19 x 1.67 x 10-27 kg

m = 3.2 x 10-26 kg

specific charge = - 1.6 x 10-19/3.2 x 10-26

= - 5.0 x 106 C/kg

But we ignore the sign as we are only asked for the magnitude.

(Choice C)

 

Q3. The Rutherford scattering experiment led to:

A
 the discovery of the electron.
B
 the quark model of hadrons.
C
 the discovery of the nucleus.
D
 evidence for wave-particle duality.