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3 years ago

Which terms are associated with the Cenozoic era: Homo sapiens, mammoth, dinosaur, grass?

Chemistry

1 answer:

abruzzese [7]3 years ago

4 0

Mammoths and dinosaurs lived in the Cenozoic era, and there was also grass. Your answers are Mammoth, dinosaur, grass.

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A beach ball has a mass of 5 g and a volume of 20 cm3. What is the object's density?

ivann1987 [24]

Mass = 5 g

volume = 20 cm³

density = mass / volume

therefore:

D = m / V

D = 5 / 20

D = 0.25 g/cm³

3 0

4 years ago

The subshell letter:a) specifies the 3-D shape of the orbital.b) specifies the principal shell of the orbital.c) specifies the p

Dafna11 [192]

Answer:

a) specifies the 3-D shape of the orbital

Explanation:

To determine the region where is more probable to find the electron, it is characterized by four quantum numbers:

- Principal quantum number (n): represents the level, or shell, where the electron is. It varies from 1 to 7, and are represented by the letters K, L, M, N, O, P, and Q.

-Azimuthal quantum number (l): represents the sublevel, or subshell. Is represented by the letters s, p, d, f, g, ... And by the numbers 0, 1, 2, 3, ... Each one has a 3-D shape, the s, for example, has a spherical shape.

-Magnetic quantum number (ml): represents the orbital inside the subshell, and varies from -l to +l, passing by the 0. Each orbital can have at least 2 electrons.

-Spin quantum number (ms): represents the spin of the electron, which can be +1/2 or -1/2.

3 0

3 years ago

The substance oxidized causes the other substance to be reduced and is called the:.

blsea [12.9K]

Answer:hydrogen Peroxide

Explanation:

4 0

3 years ago

Read 2 more answers

A 99.8 mL sample of a solution that is 12.0% KI by mass (d: 1.093 g/mL) is added to 96.7 mL of another solution that is 14.0% Pb

andre [41]

Answer:

$m_{PbI_2}=18.2gPbI_2$

Explanation:

Hello,

In this case, we write the reaction again:

$Pb(NO_3)_2(aq) + 2 KI(aq)\rightarrow PbI_2(s) + 2 KNO_3(aq)$

In such a way, the first thing we do is to compute the reacting moles of lead (II) nitrate and potassium iodide, by using the concentration, volumes, densities and molar masses, 331.2 g/mol and 166.0 g/mol respectively:

$n_{Pb(NO_3)_2}=\frac{0.14gPb(NO_3)_2}{1g\ sln}*\frac{1molPb(NO_3)_2}{331.2gPb(NO_3)_2} *\frac{1.134g\ sln}{1mL\ sln} *96.7mL\ sln\\\\n_{Pb(NO_3)_2}=0.04635molPb(NO_3)_2\\\\n_{KI}=\frac{0.12gKI}{1g\ sln}*\frac{1molKI}{166.0gKI} *\frac{1.093g\ sln}{1mL\ sln} *99.8mL\ sln\\\\n_{KI}=0.07885molKI$

Next, as lead (II) nitrate and potassium iodide are in a 1:2 molar ratio, 0.04635 mol of lead (II) nitrate will completely react with the following moles of potassium nitrate:

$0.04635molPb(NO_3)_2*\frac{2molKI}{1molPb(NO_3)_2} =0.0927molKI$

But we only have 0.07885 moles, for that reason KI is the limiting reactant, so we compute the yielded grams of lead (II) iodide, whose molar mass is 461.01 g/mol, by using their 2:1 molar ratio:

$m_{PbI_2}=0.07885molKI*\frac{1molPbI_2}{2molKI} *\frac{461.01gPbI_2}{1molPbI_2} \\\\m_{PbI_2}=18.2gPbI_2$

Best regards.

5 0

3 years ago

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Most plants and all animals depend on _____ to meet their need for nitrogen.

kirill115 [55]

They depend on nitrogen-fixing bacteria, which convert atmospheric nitrogen into a usable form.

3 0

3 years ago

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