Which statement about a physical and chemical changes is true?
a) a change in color often occurs during a chemical change.
b) a change of state of matter always indicates a chemical change.
c) if no change in color is visible in a process, it must be a chemical change.
d) if no change of state of matter occurs in a process, it must be a physical change.

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Each trait of a plant is determined a. an allele b. one gene c. a pair of genes d. one dominant gene

Iron reacts with oxygen to produce iron oxide (rust). this reaction is represented in an equation as 4fe + xo2 → 2fe2o3. identify the value of x that will balance the equation.

Grade 91.)the gravitational pull from the moon words).2.) what is the rate of gravitational 3.)if you drop a hammer, is it more likely to drop handle side down, head side down, or equal chance that it will land either way? why? 4.)a car moves 60km east and 90km west. a.) what is the distance the car traveled? b.) what is the car's displacement5.)what is the average velocity of a car that moved 60 km south in 3 hours? 6.) a car starts from rest and acceleration to 60 m/s over a time of 5 seconds. what is the acceleration of the car? 7.)what is the speed of an object at rest?