What is the pH scale for sodium hydroxide solution

Sodium hydroxide does not have a pH number. The pH of a solution of sodium hydroxide depends entirely on the concentration of it in that solution.

Some common bases as sodium hydroxide, ammonia and more

BaseNormalitypH

Sodium benzoate0.1N8.0

Sodium bicarbonate (baking soda)0.1 N8.4

Sodium carbonate (washing soda)0.1 N11.6

Sodium hydroxide (caustic soda)N14.0

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.