Which of the following is/are not true for `x-`rays?

Options

A. A.Wavelength of continuous x-rays does not depends on potential difference
B. B.Wavelength of discreate x-rays does not depends on potential difference
C. C.Discrete x-rays have energy of the order of MeV
D. D.Continuous x-rays have energy of the order of KeV

Answer

To determine which statements about X-rays are not true, let's analyze the options step by step.

### Step 1: Analyze Option A
**Statement:** The wavelength of continuous X-rays does not depend on the potential difference.

**Explanation:** Continuous X-rays are produced when high-energy electrons collide with a target material. The energy of these electrons is determined by the potential difference applied. Therefore, the wavelength of continuous X-rays is indeed dependent on the potential difference.

**Conclusion:** This statement is **not true**.

### Step 2: Analyze Option B
**Statement:** Discrete X-rays do not depend on the potential difference.

**Explanation:** Discrete X-rays, also known as characteristic X-rays, are produced when electrons transition between energy levels in an atom. The energy of these X-rays is characteristic of the element and does not depend on the potential difference.

**Conclusion:** This statement is **true**.

### Step 3: Analyze Option C
**Statement:** Discrete X-rays have energy in the order of mega electron volts.

**Explanation:** Discrete X-rays typically have energies in the range of 100 to 200 kilo electron volts (keV), not mega electron volts (MeV). Therefore, this statement is incorrect.

**Conclusion:** This statement is **not true**.

### Step 4: Analyze Option D
**Statement:** Continuous X-rays do not have energy in the order of kilo electron volts; they have energy in mega electron volts.

**Explanation:** Continuous X-rays can have energies that typically range from a few keV to several hundred keV, depending on the potential difference applied. They do not reach the order of MeV in typical X-ray production.

**Conclusion:** This statement is **not true**.

### Final Answer
The statements that are **not true** for X-rays are:
- Option A
- Option C
- Option D