Answer: The kilograms of water must evaporate from 8kg of a 25% salt solution to produce 40% salt solution is 3 kg.
Explanation:
According to the ratio and proportion:

where,
= concentration of ist solution = 25%
= mass of ist solution = 8 kg
= concentration of second solution = 40%
= mass of second solution = ? kg


Thus the final solution must have a mass of 5 kg , i.e (8-5)= 3 kg of mass must be evaporated.
Therefore, the mass that must be evaporated from 8kg of a 25% salt solution to produce 40% salt solution is 3 kg.
Answer:
The volume is 
Explanation:
From the question we are told that
The number of moles of the gas is 
The volume of the gas is 
The of moles of the gas that leaked is 
Generally from the ideal gas law
Generally at constant pressure and temperature

So 
=> 
=>
=> 
Answer:

Explanation:
The density formula is:

Rearrange this formula for v, volume. Multiply by v, then divide by d.




Volume can be found by dividing the mass by the density. The mass of the aluminum is 45.6 grams and the density is 2.1 grams per milliliter.

Divide. Note the grams, or g, will cancel out.


The volume of the aluminum is 21.7142857 milliliters.
Answer:
Velocity = 120 km/h in north
Speed = 120 km/h
Explanation:
Given data:
Distance = 300 km north
Time taken = 2.5 hr
Speed and velocity = ?
Solution:
Speed = distance / time
Speed = 300 km / 2.5 h
Speed = 120 km/h
Velocity = change in position / change in time
Velocity = 300 km north / 2.5 hr
Velocity = 120 km/h in north