Which of the following most likely has a fixed shape. helium gas, solid iron, liquid octane, hydrogen plasma

Option (b) is the correct answer.

Explanation:

An object whose molecules are attached together by strong force of attraction will most likely to have definite shape. This type of object is known as a solid object.

Whereas an object in which molecules are held less tightly is defined as a liquid. On the other hand, an object whose molecules are loosely held by weak vander waal forces is known as a gas.

Thus, we can conclude that out of the given options, solid iron will most likely has a fixed shape.

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