Which of these is an example of a physical change? a) iron melting b) steel rusting c) paper burning d) wood decaying

Option (A) is the correct answer.

Explanation:

A change in chemical reaction which results in the formation of new compounds is known as a chemical change whereas a chemical reaction in which there is no formation of any new compounds is known as a physical change.

For example, rusting of iron is a chemical change and melting of ice is a physical change.

Therefore, out of the given options iron melting is a physical change because melting causes change in intermolecular forces and no formation of any new products.

Thus, iron melting is a physical change.

a: 45.9 meters

b: 4.29 seconds

step-by-step explanation:

a: h(t)=1/2(-9.8)(3)^2+0(3)+90

h(t)=-4.9(3)^2+90

h(t)=-44.1+90

h(t)=45.9 meters

b: 0=1/2(-9.8)(t^2)+0t+90

0=-4.9t^2+90

-90=-4.9t^2

18.37=t^2

t=4.29 seconds

in the second question, the numbers aren't exact, but they're a close approximation.

all eukaryotic cell have mitochondria : )