Consider the following statements
I.Henry Moseley observed regularities in the characteristics of X ray spectra of elements
II.A plot of frequency of X rays emitted against atomic number (Z) give a straight line
III.The atomic number of element is equal to the number of neutron(s)in a neutral atom
IV.Electron configuration of an atom determine the physical and chemical properties
Choose the correct statement

Options

A. only I
B. I and III
C. I,II and IV
D. II,III,and Iv

Answer

To solve the question, we need to analyze each statement one by one and determine their correctness based on our knowledge of chemistry and the contributions of Henry Moseley.

### Step-by-Step Solution:

1. **Statement I: Henry Moseley observed regularities in the characteristics of X-ray spectra of elements.**
- **Analysis:** This statement is correct. Henry Moseley conducted experiments that involved the X-ray spectra of elements, leading to the discovery of the atomic number as a more fundamental property than atomic mass in the periodic classification of elements.

2. **Statement II: A plot of frequency of X-rays emitted against atomic number (Z) gives a straight line.**
- **Analysis:** This statement is also correct. Moseley found that when he plotted the frequency of the emitted X-rays against the atomic number, the relationship was linear, confirming the periodic nature of the elements based on atomic number.

3. **Statement III: The atomic number of an element is equal to the number of neutron(s) in a neutral atom.**
- **Analysis:** This statement is incorrect. The atomic number (Z) is defined as the number of protons in the nucleus of an atom. In a neutral atom, the number of electrons equals the number of protons, but the number of neutrons can vary (leading to isotopes). Therefore, atomic number does not equal the number of neutrons.

4. **Statement IV: Electron configuration of an atom determines the physical and chemical properties.**
- **Analysis:** This statement is correct. The electron configuration of an atom determines how it interacts with other atoms, which in turn influences its physical and chemical properties.

### Conclusion:
The correct statements are I, II, and IV.

### Final Answer:
The correct statements are: I, II, and IV.

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