Question

Which of the following pairs of elements have same number of valence electrons? (1) Sodium and magnesium (2) Carbon and nitrogen (3) Oxygen and sulphur (4) Potassium and calcium

Answer 1

The pair of elements with the same number of valence electrons are 3)oxygen and sulfur, as they both belong to group 16 of the periodic table and have six valence electrons each.

Step-by-step explanation:

The student is asking which pairs of elements have the same number of valence electrons. Elements in the same group of the periodic table have the same number of valence electrons. Based on the provided information, from the pairs listed, oxygen and sulfur have the same number of valence electrons because they are both in group 16, the chalcogens, which have six valence electrons.

Here are the explanations for the other pairs:

• (1) Sodium (group 1) has one valence electron, and magnesium (group 2) has two valence electrons.
• (2) Carbon (group 14) has four valence electrons, and nitrogen (group 15) has five valence electrons.
• (4) Potassium (group 1) has one valence electron, and calcium (group 2) has two valence electrons.

Answer 2

The correct answer is 3.) Oxygen (O) and sulphur (S) are the correct pair of elements that have the same number of valence electrons, which is six since they belong to the same group on the periodic table.

Step-by-step explanation:

The question seeks to identify which pair of elements have the same number of valence electrons. Valence electrons are the electrons in the outer shell of an atom and determine the chemical properties and reactivity of the element. By examining the periodic table, we can determine:

Sodium (Na) and magnesium (Mg) are in different groups; sodium has one valence electron while magnesium has two.

Carbon (C) and nitrogen (N) are adjacent in the periodic table with carbon having four valence electrons and nitrogen having five.

Oxygen (O) and sulphur (S) are in the same group (oxygen family) and both have six valence electrons.

Potassium (K) and calcium (Ca) are in different groups; potassium has one valence electron and calcium has two.

Hence, the pair of elements that have the same number of valence electrons is Oxygen and sulphur.