The electronic configuration of four elements are:
(I) `[Kr]5s^(1)`
(II) `[Rn]5f^(14)6d^(1)7s^(2)`
(III) `[Ar]3d^(10)4s^(2)4p^(5)`
(IV) `[Ar]3d^(6)4s^(2)`
Consider the following statements:
(I I shows variable oxidation state
(ii) II is a d-block element
(iii) The compound formed between I and III is covalent
(iv) IV shows single oxidation state
which statement is true (T) or false (F)?

Options

A. FTFF
B. FTFT
C. FFTF
D. FFFF

Explanation

To solve the question, we need to analyze each statement regarding the electronic configurations of the four elements provided. Let’s go through each statement step by step.

### Step 1: Analyze Statement I
**Statement I:** "I shows variable oxidation state."

- The electronic configuration of element I is `[Kr]5s^1`.
- This indicates that element I has one electron in its outermost shell (5s).
- Elements with a single electron in their outermost shell typically do not show variable oxidation states; they usually exhibit a +1 oxidation state when they lose that one electron.

**Conclusion:** This statement is **False**.

### Step 2: Analyze Statement II
**Statement II:** "II is a d-block element."

- The electronic configuration of element II is `[Rn]5f^(14)6d^(1)7s^(2)`.
- The last electron enters the 6d subshell, which means it is indeed a d-block element.
- However, since it has filled 5f subshells, it is primarily classified as an f-block element, not a d-block element.

**Conclusion:** This statement is **False**.

### Step 3: Analyze Statement III
**Statement III:** "The compound formed between I and III is covalent."

- Element I has the configuration `[Kr]5s^1`, and element III has the configuration `[Ar]3d^(10)4s^(2)4p^(5)`.
- Element I can lose one electron (forming a cation), while element III can gain one electron to achieve a stable noble gas configuration (forming an anion).
- The bond formed between a metal (I) and a non-metal (III) through the transfer of electrons is typically ionic, not covalent.

**Conclusion:** This statement is **False**.

### Step 4: Analyze Statement IV
**Statement IV:** "IV shows single oxidation state."

- The electronic configuration of element IV is `[Ar]3d^(6)4s^(2)`.
- This configuration corresponds to iron (Fe), which can exhibit multiple oxidation states, such as +2 and +3, due to the ability to lose different numbers of electrons from the 3d and 4s subshells.

**Conclusion:** This statement is **False**.

### Final Summary
After analyzing all four statements:
1. Statement I: False
2. Statement II: False
3. Statement III: False
4. Statement IV: False

All statements are false.