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3 years ago

Which is more likely in a settled and sedentary community?

Chemistry

1 answer:

Andre45 [30]3 years ago

4 0

Answer:

Mar 29, 2015 · Their settlements are much more permanent and include houses, storage buildings, etc. They also need preservation methods and storage techniques, unlike the nomads. Sedentary Societies were first to be seen near waterways such as rivers.

Explanation:

You might be interested in

The number of protons in an atom is known as that element's .........................

lawyer [7]

In chemistry and physics, the atomic number of a chemical element (also known as its proton number) is the number of protons found in the nucleus of an atom of that element, and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z.

8 0

3 years ago

All of the following statements about different elements are true EXCEPT:a) barium is an alkali earth metalb) manganese is a tra

stich3 [128]

Answer:

The statement that is not true is: c) Sulfur is considered a metalloid

Explanation:

To answer this kind of questions your best tool is a periodic table.

The periodic table shows the elements ordered by increasing atomic number (number of protons), in an arragement of rows and columns. In such arrangement, the elements appear classified as metals, non-metals, and metaloids.

Roughly metals are on the left side of the table, nonmetals are on the right side, and metalloids are a reduced group that are in a kind of step ladder dividing the metals and nonmetals.

With that, you can follow this procedure for each of the answer choices:

a) Barium is an alkali earth metal:

TRUE. Barium, Ba, has atomic number 56, is in the column (group) number 2, which is the group of the alkali earth metals.

b) Manganese is a transition metal:

TRUE. Manganese, Mn, has atomic number 25 and is in the column 7. The columns 3 through 12 enclose the transition metals. So, manganese is a transition metal.

c) Sulfur is considered a metalloid.

FALSE. Sulfur, S, has atomic number 16, is in the column 16, (right below oxygen) and is classified as a nonmetal.

d) Krypton is one of the noble gasses

TRUE. Krypton, Kr, has atomic number 36, and is in the column 18. This column includes all the noble gases, which are elements whose valence shells are complete (2 electrons in the case of He and 8 electrons in all the other cases).

This group is named noble gases because the elements have very low reactivity, so they are almos inert.

e) Iodine is a halogen

TRUE. Iodine, I, is the element with atomic number 53, and is in the column 17. This column includes all the halogens (F, Cl, Br, I, At, and the most recently discovered Ts).

6 0

4 years ago

Humans have three types of cone cells in their eyes, which are responsible for color vision. Each type absorbs a certain part of

harkovskaia [24]

Answer:

The frequency of this light is $6.98\times 10^{14} s^{-1}$ .

Explanation:

Wavelength of the light = $\lambda = 430 nm=4.30\times 10^{-7} m$

Speed of the light = c = $= 3\times 10^8 m/s$

Frequency of the light = $\nu$

$\nu =\frac{c}{\lambda }$

$\nu =\frac{3\times 10^8 m/s}{4.30\times 10^{-7} m}=6.98\times 10^{14} s^{-1}$

The frequency of this light is $6.98\times 10^{14} s^{-1}$ .

5 0

4 years ago

Consider the following hypothetical aqueous reaction. A flask is charged with .065 mol of A in a total volume of 100.0 mL. The f

Inga [223]

Answer: 0.422 M⁻¹s⁻¹

Explanation: Reaction Rate is the speed of decomposition of the reactant(s) per unit of time.

A Rate Law relates concentration of reactants, rate reaction and rate constant:

$r=k[A]^{x}[B]^{y}$

where

[A] and [B] are reactants concentration

x and y are reaction order, not related to the stoichiometric coefficients

k is rate constant

r is rate

Before calculating rate constant, first we have to determine reaction order.

In this question, the reactio order is 2. So, the rate law for it is

$-\frac{d[A]}{dt} =k[A]^{2}$

and the integrated formula is

$\frac{1}{[A]} =\frac{1}{[A]_{0}} +kt$

in which

[A]₀ is initial concentration of reactant

Then, using initial concentration at initial time and final concentration at final time:

$\frac{1}{0.031} =\frac{1}{0.065} +k(40)$

$40k=\frac{1}{0.031}-\frac{1}{0.065}$

$40k=32.26-15.38$

k = 0.422

The rate constant for the reaction is 0.422 M⁻¹.s⁻¹

3 0

3 years ago

In the background information, it was stated that CaF2 has solubility, at room temperature, of 0.00160 g per 100 g of water. How

____ [38]

Answer:

2.05*10⁻⁵ moles of CF₂ can dissolve in 100 g of water.

12.82 moles of CaF₂ will dissolve in exactly 1.00 L of solution

Explanation:

First, by definition of solubility, in 100 g of water there are 0.0016 g of CaF₂. So, to know how many moles are 0.0016 g, you must know the molar mass of the compound. For that you know:

Ca: 40 g/mole
F: 19 g/mole

So the molar mass of CaF₂ is:

CaF₂= 40 g/mole + 2*19 g/mole= 78 g/mole

Now you can apply the following rule of three: if there are 78 grams of CaF₂ in 1 mole, in 0.0016 grams of the compound how many moles are there?

$moles=\frac{0.0016 grams*1 mole}{78 grams}$

moles=2.05*10⁻⁵

2.05*10⁻⁵ moles of CF₂ can dissolve in 100 g of water.

Now, to answer the following question, you can apply the following rule of three: if by definition of density in 1 mL there is 1 g of CaF₂, in 1000 mL (where 1L = 1000mL) how much mass of the compound is there?

$mass of CaF_{2}=\frac{1000 mL*1g}{1mL}$

mass of CaF₂= 1000 g

Now you can apply the following rule of three: if there are 78 grams of CaF₂ in 1 mole, in 1000 grams of the compound how many moles are there?

$moles=\frac{1000 grams*1 mole}{78 grams}$

moles=12.82

12.82 moles of CaF₂ will dissolve in exactly 1.00 L of solution

5 0

3 years ago