Answer:
1. A substance that can be separated into two or more substances only by a chemical change is a(n) _____.
solution
element
mixture
compound
2.
Which of the following materials is a substance?
air
gasoline
stainless steel
silver
3.
The first figure in a properly written chemical symbol always is _____.
boldfaced
capitalized
italicized
underlined
4.
Which of the following represents a compound?
H
H-3
H2O
O-16
5. What do chemical symbols and formulas represent, respectively?
elements and compounds
atoms and mixtures
compounds and mixtures
elements and ions
Explanation:
Density of powder 1 = 0.5 g / 45 cm^3 = 1/90 g/cm^3
Density of powder 2 = 1.3 g / 65 cm^3 = 1/50 g/cm^3
Therefore the densities of the two powders are different, hence chemical reaction has occurred.
(note: none of the other choices make sense. In fact, a different density does not necessarily indicate a chemical change, see paragraph below).
Density of powders are not definitive unless they are each of the same size and texture. For example, granular sugar, rock sugar, and icing sugar all have different densities. I would conclude that this experiment does not lend to a reliable answer.
Yes, while he is sitting he is reading something to prepare him to finsh a job. reading instructions can be considered step one in starting a job. ex-before builders are able build, they must read the blueprints in order to know what to do.
Answer:
Number of slices of pizza is 993.
Explanation:
It is given that, in one slice of "everything" pizza there are 650 Calories. The conversion factor from calories to joules is :
1 calorie = 4.184 joules
650 calories = 2719.6 joules
Total energy in the pizza, E = 2700000 J
Let there are n number of slices of pizza. It is given by :
n = 992.79
or
n = 993
So, there are 993 slices of pizza. Hence, this is the required solution.
Answer: A medium is any substance or region through which a wave is transmitted. The speed of a wave is dependant on four factors: wavelength, frequency, medium, and temperature. Wave speed is calculated by multiplying the wavelength times the frequency (speed = l * f).
