Answer: C) Elements and pure compounds are homogeneous materials because they have a uniform composition throughout.
Explanation: Element is a pure substance which is composed of atoms of similar elements. Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.
Elements are compounds form homogeneous materials as they have uniform composition throughout and the components are evenly distributed throughout the material.
Mixtures are heterogeneous materials as they do not have uniform composition and the components are not evenly distributed throughout the material.
I think that a writer may use all of the following techniques to lead the reader to a flashback EXCEPT: a. a memory
Answer:
The correct answer is 1 millon years.
Explanation:
Fossil rocks serve to study the evolution of species throughout history. Species usually adapt to survive the changing environment around them. Given this fact, we can deduce that the oldest species were very different from the way they are today. This means that the current species are more similar to those that preceded them more recently. The fossil of 1 million years ago is the most similar to today's horse.
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Electron configuration
an element A has 3 shells and has 3 valence electrons
so electron configuration of A: 1s², 2s², 2p⁶, 3s², 3p¹
will tend to lose 3 electron to form a cation: A³⁺
a. Nitrate of A
A(NO₃)₃
b. Chloride of A
ACl₃
c. Oxide of A
A₂O₃
The correct answer is 96.80 grams
Explanation:
The density of a substance shows the total mass the substance contains in 1 mL or 1 cm3 as density is calculated by using the formula D= M (mass) / V (volume). This implies, Iron contains 7.87 grams per milliliter. Moreover, this value and formula can be used to calculate the mass or volume of any other sample. The process to calculate the mass of an iron sample with a volume of 12.3 mL is shown below.
D = M ÷ V
7.87 mL = x ÷ 12.3 mL - x represents the missing value. Now find the value of x by solving the equation
x = 7.87 · 12.3
x = 96.80
This means a sample of 12.3 mL contains a mass of 96.80 grams. Also, you can know this value is correct because if you divide the mass by the value the density is the same (96.80 grams ÷ 12.3 mL = 7.87 g/mL)
