Which of the following statements is/are correct?

Options

A. Isotopes have same number of nucleus
B. Isobars have same number of protons
C. Isotones have same number of neutrons
D. Isobars are atoms of different elements with same isotopic number.

Explanation

To determine which statements about isotopes, isobars, and isotones are correct, we will analyze each statement step by step.

### Step 1: Understanding Isotopes
- **Definition**: Isotopes are atoms of the same element that have the same atomic number (number of protons) but different mass numbers (number of protons + neutrons).
- **Example**: Hydrogen (H) has an atomic number of 1 and a mass number of 1 (1 proton, 0 neutrons). Deuterium (D), another isotope of hydrogen, has the same atomic number (1 proton) but a mass number of 2 (1 proton + 1 neutron).

**Hint**: Remember that isotopes have the same number of protons but different numbers of neutrons.

### Step 2: Evaluating the First Statement
- The first statement claims that isotopes have the same atomic number and different mass numbers. This is **correct**.

### Step 3: Understanding Isobars
- **Definition**: Isobars are atoms of different elements that have the same mass number but different atomic numbers.
- **Example**: Calcium (Ca) and Argon (Ar) can be isobars if they both have a mass number of 40 but different atomic numbers.

**Hint**: Isobars have the same mass number but belong to different elements.

### Step 4: Evaluating the Second Statement
- The second statement claims that isobars have the same mass number but different atomic numbers. This is also **correct**.

### Step 5: Understanding Isotones
- **Definition**: Isotones are atoms that have the same number of neutrons but different atomic numbers and mass numbers.
- **Example**: Carbon-14 (6 protons, 8 neutrons) and Nitrogen-15 (7 protons, 8 neutrons) are isotones.

**Hint**: Isotones share the same number of neutrons.

### Step 6: Evaluating the Third Statement
- The third statement claims that isotones have the same number of neutrons. This is **correct**.

### Step 7: Evaluating the Fourth Statement
- The fourth statement discusses isobars and states that they are atoms of different elements with the same isotopic number. This is **incorrect** because isobars have different isotopic numbers.

### Conclusion
After evaluating all statements:
1. The first statement about isotopes is **correct**.
2. The second statement about isobars is **correct**.
3. The third statement about isotones is **correct**.
4. The fourth statement about isobars is **incorrect**.

### Final Answer
The correct statements are the first, second, and third statements.