atomic structure

1. An atom has an atomic number of 12 and a mass number of 25. The number of electrons in the atom is

• 12

• 13

• 25

• 37

2. The relative atomic mass of an element is

• The absolute mass of an atom of the element.

• The total mass of protons and neutrons in its nucleus.

• The average mass of an atom of the element as it occurs in nature, relative to the ¹²C = 12.000 00 scale.

• The average mass number of different isotopes of the element relative to the ¹²C = 12.000 00 scale.

3. Which of the following statements can explain why noble gases are stable?

• They are all gases at room temperature.

• They are Group 0 elements.

• They have eight electrons in their outermost shells.

• They are all elements.

4. Which of the following elements is a metal?

• Aluminium

• Carbon

• Germanium

• Neon

5. Which of the following elements does NOT conduct electricity?

• Bromine

• Graphite

• Magnesium

• Gold

6. Which of the following elements is a solid at room temperature and pressure?

• Cl

• N

• Ne

• S

7. An atom has 28 electrons and 30 neutrons. Which of the following combinations about the atom is correct?

• Atomic no.: 28 Mass no.: 30

• Atomic no.: 28 Mass no.: 58

• Atomic no.: 30 Mass no.: 28

• Atomic no.: 58 Mass no.: 28

8. An isotope of an element (atomic number z) has a mass number of 2z + 4. How many neutrons are in the nucleus of the isotope?

• z + 4

• z + 2

• z

• 4

9. Which of the following represents the electronic arrangement of an atom of a metalloid?

• 2,8,1

• 2,8,2

• 2,8,3

• 2,8, 4

10. Which of the following statements about metalloids is / are correct ?

(1) Germanium is a metalloid.

(2) Metalloids cannot conduct electricity at room temperature.

(3) Some metalloids are gases.

• (1) only

• (2) only

• (1) and (3) only

• (2) and (3) only