Which of the following is least reactive?

Correct option is D

The correct answer is (d) Mg (Magnesium)

Explanation:

The reactivity of metals is determined by their ability to lose electrons easily. Metals from Groups 1 and 2 in the periodic table are highly reactive. Among the given options:

1. Sodium (Na) and Potassium (K) belong to Group 1 (Alkali Metals) and are highly reactive.
2. Calcium (Ca) belongs to Group 2 (Alkaline Earth Metals) and is moderately reactive.
3. Magnesium (Mg) also belongs to Group 2, but it is less reactive than calcium because of its smaller atomic size and higher ionization energy.

Thus, Magnesium (Mg) is the least reactive among the given metals.

Information Booster:

Reactivity of Alkali Metals (Group 1):

• K > Na (Potassium is more reactive than Sodium).
• They react violently with water to form hydroxides and release hydrogen gas.

Reactivity of Alkaline Earth Metals (Group 2):

• Ca > Mg (Calcium is more reactive than Magnesium).
• Calcium reacts with cold water, whereas Magnesium reacts with hot water or steam.

General Trend in Metal Reactivity:

Increases down a group (K is more reactive than Na, and Ca is more reactive than Mg).

Decreases across a period (Na is more reactive than Mg).

Additional Knowledge:

• Highly Reactive Metals: K, Na, Ca
• Moderately Reactive Metals: Mg, Al, Zn, Fe
• Least Reactive Metals (Noble Metals): Cu, Ag, Au, Pt