Chemistry
Given below are four ions:
Cl-, Li+, Al3+, K+
Identify the pair of ions which have the same electronic configuration.
[Atomic number: Cl = 17, Li = 3, Al = 13, K = 19]
- Cl- & Li+
- Al3+ & K+
- Cl- & K+
- Li+ & K+
Answer
Cl- & K+
Reason
- Chlorine has atomic number 17. Its neutral atom contains 17 electrons with the configuration 2, 8, 7. When it gains one electron to form Cl⁻, it has 18 electrons, giving the configuration 2, 8, 8 (the same as argon).
- Potassium has atomic number 19. A neutral K atom has the configuration 2, 8, 8, 1. When it loses one electron to form K⁺, it is left with 18 electrons, also giving the configuration 2, 8, 8.
Because both Cl⁻ and K⁺ possess 18 electrons and share the electron configuration 2, 8, 8, they form the required pair with identical electronic configurations.
Related Questions
Which of the following options has all the compounds which are members of the same homologous series?
- CH4, C2H6, C3H8
- CH4, C2H6, C3H6
- C3H4, C3H6, C3H8
- C2H4, C3H6, C4H10
Assertion (A): In the Contact Process SO3 gas is not directly dissolved in water to obtain sulphuric acid.
Reason (R): Dense fog or misty droplets of sulphuric acid are formed which is difficult to condense.
- Both (A) and (R) are true, and (R) is the correct explanation of (A).
- Both (A) and (R) are true, and (R) is not the correct explanation of (A).
- (A) is true but (R) is false.
- (A) is false but (R) is true.
Which pair of reactants can be best used to produce lead (II) sulphate?
- Sulphuric acid + Lead
- Sulphuric acid + Lead hydroxide
- Sodium sulphate + Lead nitrate
- Potassium sulphate + Lead oxide
Aqueous copper (II) sulphate is electrolysed using copper electrodes. Which statement about the electrolysis is not correct?
- An oxidation reaction occurs at the positive electrode.
- The current is carried through the electrolyte by ions.
- The positive electrode loses mass.
- The number of copper (II) ions in the electrolyte decreases.