I knew we usually say how much weight of, but I am wondering if I can say what is the weight of, as I came across some sentences like what's area of. why do we need collocate what with area rather than how much or there is no rule for this, it just sound natural to you?
1) What is the weight of this cabbage? [that's fine]
How much does this cabbage weigh. [But people often say it like that.]
2) What's the area of this room? [fine]
How large is this room? [Often said like that]
This is true of most weights and measurements in everyday life/conversation
How much does x weigh? How high is X? How big is x? [for an area in square feet or meters or yards, acres, etc.] How long is x? How wide is x?
All those can be said as: What is the weight, height, size, length, width of x.
There are two ways to express all these things in English. Both can be used. And both are used. But the ones with how are what you hear in everyday speech.