As with the properties of a substance, the changes that substances undergo can be classified as either physical or chemical. During physical changes a substance changes its physical appearance, but not its composition. The evaporation of water is a physical change.
(I searched that up but here’s an explanation with my own words that you can use):
Change in matter can be classified as a physical change as well as a chemical change due to the properties of substance. A physical change changes substance within its appearance but not its composition. For an example: The evaporation of water is a physical change.
There you go hopefully that helped
What do you need help on which problem
1.
The balanced chemical reaction is:
N2 +3 I2 = 2NI3
We are given the amount of product formed.
This will be the starting point of our calculations.
3.58 g NI3 ( 1 mol NI3 / 394.71 g NI3 ) ( 3
mol I2 / 2 mol NI3 ) = 0.014 mol I2.
Thus, 0.014 mol of I2 is needed to form the
given amount of NI3.
Answer:
Explanation:
Given that,
The dimensions of the board is 5.54 cm x 10.6 cm X 199 cm.
The mass of the board is 28.6 kg.
Since, 1 kg = 1000 grams
28.6 kg = 28.6 × 1000 g = 28600 grams
Density = mass/volume
So,
So, the density of a board is 
.
