Which of the following statements is not true

Options

A. Paramagnetic substances are weakly attracted by magnetic field
B. Ferromagnetic substances cannot be magnetised permanently
C. The domains in antiferromagnetic substances are oppositely oriented with respect to each other
D. Pairing of electrons cancels their magnetic moment in the diamagnetic substances

Explanation

To determine which statement is not true regarding paramagnetic substances, let's analyze the characteristics of paramagnetism step by step.

### Step 1: Understanding Paramagnetic Substances
Paramagnetic substances are materials that have unpaired electrons. These unpaired electrons create a net magnetic moment, which allows the substance to be attracted to an external magnetic field.

**Hint:** Look for the presence of unpaired electrons in the material to identify paramagnetic substances.

### Step 2: Magnetic Attraction
Paramagnetic substances are weakly attracted to magnetic fields. This means that when placed in a magnetic field, they will experience a force that pulls them towards the field.

**Hint:** Remember that the attraction is weak compared to ferromagnetic materials.

### Step 3: Temporary Magnetization
When a paramagnetic substance is placed in a magnetic field, it becomes magnetized. However, this magnetization is temporary. Once the external magnetic field is removed, the substance will lose its magnetization.

**Hint:** Think about how the magnetic properties change when the external field is removed.

### Step 4: Permanent Magnetization
The statement that paramagnetic substances can be magnetized permanently is **not true**. Unlike ferromagnetic materials, which can retain their magnetization, paramagnetic materials do not have this property.

**Hint:** Focus on the difference between paramagnetic and ferromagnetic materials regarding their ability to retain magnetization.

### Step 5: Antiparamagnetic Substances
Antiparamagnetic substances are characterized by their magnetic domains being oppositely aligned, which results in no net magnetization. This means that they do not exhibit a net magnetic moment.

**Hint:** Consider how the alignment of magnetic domains affects the overall magnetic properties of a substance.

### Conclusion
From the analysis, the statement that "paramagnetic substances are magnetized permanently" is the one that is not true.

### Final Answer
The statement that is not true is: "Paramagnetic substances are magnetized permanently."

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