Hot air balloons have hot air inside them, which is less dense as the air around it. Thus it rises. A cold air balloon would sink because the air would be more dense than the air around it. Also, the balloon’s volume would vary in size depending on the weight of the balloon.
Explanation:
Hi for this one u just need to remember and use the equation.

then u find mr of potassium which is 39.1.
then u do

you get the answer as 0.5115 write ur answer to 3 significant figures which will be 0.512 moles .
hope this helps :)
Answer:
The amount is 
Explanation:
From the question we are told that
The distance traveled per day is 
The cost of one liter is 
The car's gas mileage is 
Generally the amount of distance covered in one week is evaluated as


The amount of gas used in one week by the car is mathematically represented as

=> 
=> 
converting to liters

Thus the amount spent on gas in one week is

=> 
=> 
The wood turns into ash and smoke so mass is nor destroyed or created.