The elements with the highest and lowest enthalpy of atomisation , respectively for first row transition elements are

Options

A. Sc , Zn
B. Ti ,Ni
C. V, Zn
D. Cr, Mn

Explanation

To determine the elements with the highest and lowest enthalpy of atomization among the first-row transition elements (from scandium to zinc), we can follow these steps:

### Step 1: Identify the first-row transition elements
The first-row transition elements are:
- Scandium (Sc)
- Titanium (Ti)
- Vanadium (V)
- Chromium (Cr)
- Manganese (Mn)
- Iron (Fe)
- Cobalt (Co)
- Nickel (Ni)
- Copper (Cu)
- Zinc (Zn)

### Step 2: Understand the concept of enthalpy of atomization
Enthalpy of atomization refers to the energy required to break the bonds in one mole of a substance to form gaseous atoms. In metals, this is related to the strength of metallic bonds, which depend on the number of unpaired electrons.

### Step 3: Analyze the number of unpaired electrons
- Elements with more unpaired electrons generally have stronger metallic bonds and thus higher enthalpy of atomization.
- Elements with no unpaired electrons will have weaker metallic bonds and lower enthalpy of atomization.

### Step 4: Determine the unpaired electrons in each element
- Sc: 3 unpaired electrons
- Ti: 2 unpaired electrons
- V: 3 unpaired electrons
- Cr: 6 unpaired electrons
- Mn: 5 unpaired electrons
- Fe: 4 unpaired electrons
- Co: 3 unpaired electrons
- Ni: 2 unpaired electrons
- Cu: 1 unpaired electron
- Zn: 0 unpaired electrons

### Step 5: Identify the element with the lowest enthalpy of atomization
Since zinc (Zn) has no unpaired electrons, it will have the lowest enthalpy of atomization among the first-row transition elements.

### Step 6: Identify the element with the highest enthalpy of atomization
Among the other elements, chromium (Cr) has the highest number of unpaired electrons (6), indicating it has the strongest metallic bonds and therefore the highest enthalpy of atomization.

### Conclusion
The elements with the highest and lowest enthalpy of atomization among the first-row transition elements are:
- Highest: Chromium (Cr)
- Lowest: Zinc (Zn)

### Final Answer:
The elements with the highest and lowest enthalpy of atomization, respectively, for first-row transition elements are Chromium (Cr) and Zinc (Zn).

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