a.

Nitrogen

b.

Aluminium

c.

Copper

d.

Sulphur

a.

Elements in the same period have the same number of valence electrons

b.

The valence electrons of the elements in the same period increase progressively across the period

c.

Elements in the same group have the same number of electron shells

d.

The non-metallic properties of the elements tend to decrease across the each period

a.

The atomic number

b.

The Avogadro number

c.

The gas constant

d.

The number of electrons

a.

be zero

b.

reduce

c.

increase

d.

be stable