The Question is from neet-chemistry the-s-block-elements , and it was created by the author Mr. S M HUSSAIN

Question

The ${\rm{C}}{{\rm{a}}^{2 + }}$  ion has the same number of electrons as:

Mr. S M HUSSAIN · Accepted Answer

## CORE INFORMATION
✓ **Answer**: [B]
## CONCEPT FRAMEWORK
	**Primary Concept**: Number of electrons in ions and neutral molecules.
	**Related Topics**: Atomic number, ionization, covalent bonding.
	**Prerequisites**: Understanding of atomic structure and how ions form.
## SOLUTION PATHWAY
**Given Information**:
	Calcium ion (${m{Ca}}^{2+}$), Magnesium ion (${m{Mg}}^{2+}$), Copper ion (${m{Cu}}^{2+}$), Neon (Ne), Ethane (${{m{C}}_2}{{m{H}}_6}$)
**Method & Steps**:
	1. Determine the number of electrons in a neutral Ca atom: Calcium (Ca) has an atomic number of 20, so a neutral Ca atom has 20 electrons.
		Reasoning: Atomic number equals the number of protons and electrons in a neutral atom.
		Formula/Rule: Atomic number = number of electrons (in a neutral atom)
	2. Determine the number of electrons in a Ca$^{2+}$ ion: The Ca$^{2+}$ ion has lost 2 electrons, so it has 20 - 2 = 18 electrons.
		Working: Subtract the charge of the ion from the number of electrons.
		Key Point: Positive ions have fewer electrons than their neutral atom.
	3. Determine the number of electrons in each of the answer choices:
		A. ${m{Mg}}^{2+}$: Magnesium (Mg) has atomic number 12, so a neutral Mg atom has 12 electrons. ${m{Mg}}^{2+}$ has 12 - 2 = 10 electrons.
		B. ${{m{C}}_2}{{m{H}}_6}$: Carbon (C) has atomic number 6 and Hydrogen (H) has atomic number 1. So, ${{m{C}}_2}{{m{H}}_6}$ has (2 * 6) + (6 * 1) = 12 + 6 = 18 electrons.
		C. ${m{Cu}}^{2+}$: Copper (Cu) has atomic number 29, so a neutral Cu atom has 29 electrons. ${m{Cu}}^{2+}$ has 29 - 2 = 27 electrons.
		D. ${m{Ne}}$: Neon (Ne) has an atomic number of 10, so it has 10 electrons.
	4. Compare the number of electrons in Ca$^{2+}$ with those in the options.
		Result: Only ${{m{C}}_2}{{m{H}}_6}$ has 18 electrons, the same as ${m{Ca}}^{2+}$.
		Verification: The count of electrons is accurate for all species.
 ## OPTION ANALYSIS
[A] :x: ${m{Mg}}^{2+}$ has 10 electrons, not 18.
[B] ✓: ${{m{C}}_2}{{m{H}}_6}$ has 18 electrons, the same as ${m{Ca}}^{2+}$.
[C] :x: ${m{Cu}}^{2+}$ has 27 electrons, not 18.
[D] :x: ${m{Ne}}$ has 10 electrons, not 18.
 ## LEARNING AIDS
	**Common Mistakes**:
		1. [Error 1]: Forgetting to adjust for the charge when calculating the number of electrons in an ion. [How to avoid]: Remember to subtract electrons for positive ions and add electrons for negative ions.
		2. [Error 2]: Incorrectly determining the number of electrons in molecules. [How to avoid]: Sum the number of electrons for each atom based on their atomic number.
	**Quick Tips**:
		1. [Helpful shortcut]: Look for isoelectronic species (same number of electrons) by comparing the number of electrons in the ion and the options.
		2. [Memory aid]: Remember that positive ions have lost electrons and negative ions have gained electrons.

Mr. S M HUSSAIN · Answer

${\rm{M}}{{\rm{g}}^{2 + }}$

Mr. S M HUSSAIN · Answer

The correct Option is "${{\rm{C}}_2}{{\rm{H}}_6}$"

Mr. S M HUSSAIN · Answer

${\rm{C}}{{\rm{u}}^{2 + }}$

Mr. S M HUSSAIN · Answer

${\rm{Ne}}$

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