Question

we can easily move hand in air but to do the same through a solid block of wood we need a karate expert

Answer 1

Hii u can move your hand in air quickly but in the place of wood we unable because it's good force of attraction between it's atom. and it is also a solid substance.

Answer 2

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d) Molecules in gases are loosely packed as compared to solid molecules which are densely packed.

Hence we are easily able to break the force of attraction when we move our hand through air but find it difficult to break through a solid (because of greater forces of attraction between molecules) which a karate expert is able to smash with the application of a lot of force.

Thanks !!