Question 1

Which statement about an atom of 23Na is correct?

  A  

it is an isomer of sodium

  B  

it has an atomic number of 23

  C  

it has 12 neutrons in its nucleus

  D  

it has a mass number of 11

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Question 2

What is a possible mass number of a magnesium isotope?


  A  

12

  B  

23.99


  C  

24

  D  

24.3

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Question 3

Which ion has a different number of electrons from the other three ions?

  A  

Ga3+

  B  

Cl-

  C  

S2-

  D  

Ca2+

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Question 4

A sample of boron contains the isotopes 10B and 11B.

The relative atomic mass of the boron sample is 10.8.

What is the percentage of 11B atoms in the sample of boron?

  A  

8.0%

  B  

20%

  C  

80%

  D  

92%

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Question 5

Which atom has the smallest number of neutrons?

  A  

3H

  B  

4He

  C  

5He

  D  

4Li

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