Which of the following statements (s) about the modern periodic table are incorrect ?
(i) The elements in the modern periodic table are arranged on the basis of their decreasing atomic numbers
(ii) The elements in the modern periodic table are arranged on the basiss of their increasing atomic mases.
(iii) Isotopes are placed in adjoining group(s) in the periodic table
(iv) The elements in the modern periodic table are arranged on the basis of their increasing atomic number.

Options

A. Only (i)
B. (i),(ii) and (iii)
C. (i), (ii) and (iv)
D. Only (iv)

Explanation

To determine which statements about the modern periodic table are incorrect, we will analyze each statement one by one.

### Step 1: Analyze Statement (i)
**Statement:** The elements in the modern periodic table are arranged on the basis of their decreasing atomic numbers.

**Analysis:** This statement is incorrect. In the modern periodic table, elements are arranged in increasing order of their atomic numbers, not decreasing.

### Step 2: Analyze Statement (ii)
**Statement:** The elements in the modern periodic table are arranged on the basis of their increasing atomic masses.

**Analysis:** This statement is also incorrect. While earlier periodic tables were based on atomic masses, the modern periodic table is organized by increasing atomic numbers, not atomic masses.

### Step 3: Analyze Statement (iii)
**Statement:** Isotopes are placed in adjoining group(s) in the periodic table.

**Analysis:** This statement is incorrect. Isotopes of an element occupy the same position in the periodic table. For example, all isotopes of carbon are placed in the same position as carbon, not in adjoining groups.

### Step 4: Analyze Statement (iv)
**Statement:** The elements in the modern periodic table are arranged on the basis of their increasing atomic number.

**Analysis:** This statement is correct. The modern periodic table is indeed organized by increasing atomic numbers.

### Conclusion
Based on the analysis:
- Incorrect statements: (i), (ii), and (iii)
- Correct statement: (iv)

### Final Answer
The incorrect statements about the modern periodic table are:
1. The elements in the modern periodic table are arranged on the basis of their decreasing atomic numbers.
2. The elements in the modern periodic table are arranged on the basis of their increasing atomic masses.
3. Isotopes are placed in adjoining group(s) in the periodic table.

The only correct statement is:
4. The elements in the modern periodic table are arranged on the basis of their increasing atomic number.

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