The correct option is this: PHYSICAL CHANGES: BREAKING THE STICKS AND BOILING THE WATER. CHEMICAL CHANGE: LIGHTNING THE FIRE.
In chemistry, a physical change refer to a change in which no new material is formed while a chemical change refers to a change in which a new material is formed. Boiling of water does not change water into another thing, even when the water changes to vapor, it will still turn to water again when it cools down, so boiling is a physical change, so also the breaking of sticks. Lightening a fire on the other hand is a chemical change because a new material is formed and the original material can not be recovered. Putting fire on the sticks will turn the sticks to ashes and the sticks can not be recovered from the ashes, so this is a chemical change.
Answer:
r= 3.2 cm
Explanation:
Given that
I= 8.7 A
B= 5.4 x 10⁻⁵ T
μo=1.25664 x 10⁻⁶
We know that magnetic filed in wire at a distance r given as


By putting the values

r=0.032 m
r= 3.2 cm
Observe that the given vector field is a gradient field:
Let
, so that



Integrating the first equation with respect to
, we get

Differentiating this with respect to
gives

Now differentiating
with respect to
gives

Putting everything together, we find a scalar potential function whose gradient is
,

It follows that the curl of
is 0 (i.e. the zero vector).
Answer:

Explanation:
According to the question
net force F = 2.20×10^6 N
displacement 
from figure , the horizontal forces are same in magnitude and opposite direction.
so , neglect these two forces.
we can take only vertical components of the force.
total force F' = F cos 19° + F cos 19°
= 2×F×cos 19° ................. (1
therefore , total work is
W = F'S
= (2F cos19)×S


Answer:
The light moves through glass, then air