Chemistry (Part-IV)

Transition metals have the following characteristics:

1. They occur in the form of colored compounds.
2. They are good conductors of heat and electricity.
3. Their shape can be changed easily.
4. They retain the property of being less electronegative.
5. They have to have tensile strength and high density.
6. They are less reactive than alkali metals like sodium.

It is clear from the above the transition metals do not tend to gain electrons.

The 15 naturally occurring metallic chemical elements with atomic numbers between 57 and 71 are called Lanthanides.

The reducing agent used in the reaction to join railway tracks (the thermite reaction) is Aluminium. Aluminium is highly reactive and reduces iron oxide to iron, generating a large amount of heat.

Transition metals are elements in the d-block of the periodic table. Looking at the options:

• Actinium (Ac) is an actinide, which is an f-block element.
• Barium (Ba) is an alkaline earth metal, an s-block element.
• Osmium (Os) is a transition metal.
• Radium (Ra) is an alkaline earth metal, an s-block element. Therefore, the elements that are not transition metals are Actinium, Barium, and Radium. Among the choices, Barium is not a transition metal.

The compound formed, sodium fluoride (NaF), is an ionic compound. Ionic compounds are good conductors of electricity in their molten state or when dissolved in water because the ions become mobile.

Therefore, the correct statement is the compound to be formed is a good conductor of electricity in a molten state.

Sodium is an alkali metal, and alkali metals are known for their softness and low density compared to many other metals. You can easily slice through a piece of sodium with a regular knife.

However, it's important to remember that sodium is also highly reactive and must be handled with care, usually stored under oil to prevent reaction with air and moisture.