A 100 gallon tank originally contains 20 gallons of water and 5lb of salt. Then, water containing .5 lb of salt per gallon is poured into the tank at a rate of 2 gal/ min. The well stirred mixture leaves at a rate of 1 gal/min. Find the amount of salt after 5 mins.

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e

i do not get it   at all

16

explanation:

the marks go by 4s

hey there!

mass = 6.75 g

volume =   9 cm³

therefore:

d = mass / volume

d   = 6.75 / 9

d = 0.7 g/cm³

answer b