Explanation

Amphoteric nature​​ Aluminium oxide is an amphoteric substance, meaning it can react with both acids and bases

It is a chemical compound of aluminium and oxygen with the chemical formula Al2O3.

Explanation

In C language, printf() function is used to print formatted output to the standard output stdout (which is generally the console screen).

The printf function is a part of the C standard library and it can allow formatting the output in numerous ways.

Explanation

A heterocyclic compound is a ring structure that contains at least one atom other than carbon in the ring.

Pyridine has a nitrogen atom in its ring structure, making it a heterocyclic compound. 

Explanation

 Bakelite is a thermosetting polymer. 

Thermosetting polymers are plastics that undergo a permanent chemical change when heated,

Forming cross-links that make them rigid and unable to be reshaped or melted after curing.

Bakelite is a classic example of a thermosetting polymer,

Formed through the condensation reaction of phenol and formaldehyde.

It is often used in applications like electrical insulation and handles. 

Explanation

 Radon is a radioactive noble gas that is used in radiotherapy for cancer treatment due to its ability to emit alpha particles, which can penetrate and damage cancer cells. 

Explanation

Knocking in an engine produces a sharp metallic sound due to premature combustion of the air-fuel mixture, which creates abnormal pressure waves.

Explanation

 A rotary kiln used in waste treatment (like incineration or cement production) typically has four zones:

   - Drying zone

   - Preheating zone

   - Combustion zone

   - Cooling zone

Explanation

Of the elements listed, aluminum is the one that most commonly exhibits a +3 oxidation state.

Sodium typically shows a +1 oxidation state, and magnesium typically shows a +2 oxidation state.

While iron can exist in a +3 oxidation state (as in iron(III) chloride),

It also commonly exists in a +2 oxidation state (as in iron(II) sulfate), making it a transition metal with variable oxidation states. 

Explanation

 Grignard reagent (RMgX) reacts with aldehydes (other than formaldehyde) to form secondary alcohols after acid hydrolysis.  

- With formaldehyde, it gives primary alcohol.  

- With ketones, it gives tertiary alcohol.

Explanation

 Lead tetroxide (Pb₃O₄), also known as red lead, crystallizes in the monoclinic crystal system.