Analyze the following group of words and identify the 'Odd One Out': Square, Rectangle, Circle, Triangle, Hexagon.

Analyze the following group of words and identify the 'Odd One Out': Apple, Banana, Orange, Carrot, Mango.

Analyze the following group of words and identify the 'Odd One Out': Copper, Iron, Zinc, Brass, Aluminum.

Analyze the following group of words and identify the 'Odd One Out': Islamabad, Kabul, Tehran, New York, Beijing.

Analyze the following group of words and identify the 'Odd One Out': Physics, Chemistry, Biology, History, Astronomy.

Identify the missing letter in the given alphabetical series: I, L, O, R, ?

In a specific numerical substitution code, if the word 'CAT' is coded as 24, and 'DOG' is coded as 26, what will be the code for the word 'BIRD'?