true or false
a. very little oxygen and nitrogen are found in air.
b. oxygen is the main cause of the formation of rust in iron.
c. impure air is odourless.
d. plants take in oxygen gas during respiration.
e. air contains water vapour. ​

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Answer:

Arginine is the most basic among them because it contains guanidine side group, −(CH2)4NHC(=NH)NH2, which is basic. Lysine has two amine groups, which makes it overall basic because of the second isolated amine group (−(CH2)4NH2). Histidine, on the other hand, contains imidazole group, which is also basic.

Explanation:

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Answer:

True

Explanation:

Answer:

A

Explanation:

We are given that the molar mass of boron triflouride BF₃ is 67.81 g/mol. We want to determine the number of molecules of BF₃ in 2 g of BF₃.

Recall that there are 6.02 × 10²³ molecules in any mole of a substance. In other words, there are 6.02 × 10²³ BF₃ molecules in a mole of BF₃. Starting with the initial value, multiply:

[tex]\displaystyle \begin{aligned} 2\text{ g BF$_3$}&\cdot \frac{1\text{ mol BF$_3$}}{67.81 \text{ g BF$_3$}} \cdot \frac{6.02\times 10^{23} \text{ molecules BF$_3$}}{1 \text{ mol BF$_3$}} \\ \\ &= 1.776 \times 10^{22} \text{ molecules BF$_3$}\end{aligned}[/tex]

Hence, our answer is A.

*Perhaps it rendered the values incorrectly, but since we started with only 2 g of BF₃, our resulting calculation should only contain one significant digit. Hence, the correct answer should be 2 × 10²² molecules of BF₃.

The molecules of  BF₃ that are there in 2 g is 1.776 × 10²² molecules and the correct option is option A.

The mole is an amount unit similar to familiar units like pair, dozen, gross, etc. It provides a specific measure of the number of atoms or molecules in a bulk sample of matter.

A mole is defined as the amount of substance containing the same number of atoms, molecules, ions, etc. as the number of atoms in a sample of pure 12C weighing exactly 12 g.

Given,

Molar mass of BF₃ = 67.81 g/mol

Mass = 2g

Moles = mass / molar mass

= 2 / 67.81

= 0.029 moles

1 mole = 6.023 × 10²³

0.029 moles = 6.023 × 10²³ × 0.029

= 1.776 × 10²² molecules

Thus, the ideal selection is option A.

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Answer:

HS(-)

HCOO(-)

SO3(2-)

SO4(2-)

S(2-)

NO2(-)

CN(-)

Explanation:

The parenthesis are the charges of the compounds. When an acid is introduced in a base, it dissociates its Hydrogens giving protons to the base. In this case, if you remove one hydrogen of a compound, you will reduce the charge of a compound since basically you're removing a positive charge from a compound. If you need to, I can explain how the thing of the charges work.

In fact, the definition of a conjugate base is a compound created when the original (an acid) compound dissacioate an atom of hydrogen (a proton) in a base.

Explanation:

What do you mean by 'how many oxygen'?

oxygen atoms? or oxygen percentage?

if oxygen atoms is 12 atoms

The mass of CO2 obtained in the reaction by stoichiometry is 30.8 g.

The equation of the reaction is;

2HCl(aq) + CaCO3(s) -----> CaCl2(aq) + H2O(l) + CO2(g)

The mass of the HCl reacted is obtained from;

Density = mass/volume

Mass = Density × volume =  1.140 g/mL ×  43.435 mL = 49.5 g

Number of moles of HCl =  49.5 g/36.5 g/mol = 1.4 moles

If 2 moles of HCl reacts produces 1 mole of CO2

1.4 moles of HCl produces x moles of CO2

x = 1.4 moles × 1 mole/ 2 moles = 0.7 moles

Mass of CO2 produced = 0.7 moles  x 44 g/mol = 30.8 g

In the second case, the same volume of acid is used hence the same mass of CO2 is obtained.

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The electronic configuration of magnesium is:

1s² 2s² 2p⁶ 3s² = [Ne] 3s²

This means that for a magnesium atom, in order to have its outermost orbital full, the easiest way would be to lose the two outermost electrons. This is seen in its relatively low first two ionization energies. The third ionization energy is several times higher because the ion would move from a stable form to an highly unstable form. (Mg⁺² → Mg⁺³ + e⁻).

Sodium only has one electron in its outermost orbital, so its first ionization energy would be several times lower than the second.

Answer:

The answer to this question is True

Answer:

0.5131M

Explanation:

NaOH(aq) + HCl(aq) — NaCl(aq) + H20(l)

Mole ratio of acid to base 1:1

(Ca × Va)/ (Cb × Vb) = Na/Nb

(0.175 × 73.3)/ (Cb × 25)= 1/1

12.8275= 25 × Cb

Cb= 12.8275/25

= 0.5131M

The charge on iron (Fe) in iron sulfate (FeSO₄) is equal to +2. Therefore, option (D) is correct.

The ionic charge can be described as the oxidation number of the chemical species. The cation carries a positive ionic charge while Anion carries a negative ionic charge. The number of electrons gained or lost by an atom decides the charge carried by ions.

In the modern periodic table, the elements placed on the left side are electropositive and act as metals because they can donate one or more electrons. The elements placed on the right side are electronegative as they can accept one or more electrons and get a negative charge on their ions.

Considering that the charge on the iron is x, We know that charge on the sulfate ion is -2.

x - 2 = 0

x = +2

Therefore, the charge on iron (Fe) in iron sulfate (FeSO₄) is +2.

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Taking into account the ideal gas law, the pressure is 2.52 atm.

An ideal gas is a theoretical gas that is considered to be composed of randomly moving point particles that do not interact with each other. Gases in general are ideal when they are at high temperatures and low pressures.

The pressure, P, the temperature, T, and the volume, V, of an ideal gas are related by a simple formula called the ideal gas law. This equation relates the three variables if the amount of substance, number of moles n, remains constant. The universal constant of ideal gases R has the same value for all gaseous substances. The numerical value of R will depend on the units in which the other properties are worked.

P×V = n×R×T

In this case, you know:

Replacing in the ideal gas law:

P×500 L = 52.1 moles ×0.082 [tex]\frac{atmL}{molK}[/tex] ×295 K

Solving:

P= (52.1 moles ×0.082 [tex]\frac{atmL}{molK}[/tex] ×295 K)÷ 500 L

P= 2.52 atm

Finally, the pressure is 2.52 atm.

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The molar volume (Vm) is the volume occupied by one mole of a chemical element or chemical compound at standard temperature and pressure (STP). The molar volume of Cl₂ is 35.10 cm³/mol.

One mole of any gas has a defined volume when it is at a particular temperature and pressure. The relationship between molar mass and molar volume is direct and inverse, respectively.

Two gases have equal molecules if their volumes are the same at a given temperature and pressure. A gas's volume is directly proportional to the number of moles it contains. One mole of any gas takes up 22.4 L of space at STP.

The expression used to calculate molar volume is:

Molar volume = Molar mass / Density

The molar mass of Cl₂ = 70.906 g/mol

Molar volume = 70.906 / 2.02

Molar volume = 35.10 cm³/mol

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Answer:

➜ Properties of liquids and gases. Liquids have a fixed volume but no fixed shape. Gases have no fixed volume and no fixed shape. Gases expand to fill the space available. They can also be compressed into a very small space.

Explanation:

12.044 × 10 ²³molecules of sulphur dioxide are 0.2 mole.

solid.................

Answer:

b solid

Explanation:

i know for a fact

Answer:

D. 17,190 years old

Answer:

6.023×10^23

Explanation:

Molecular mass= 2 (H)+1 (O) =2*1+1*16=2+16= 18 gm per 1gm molecule of water

Answer:

absorption or precipitation or by both

Explanation:

Answer:

A. 4,6-dimethyloct-1,4,6-yne

B. deconic acid

C. 3-ethyl-4-methyl-7-bromocyclohexene

D. 2,2,3-trimethyl-4-butyl-heptane

E. 3-methylhexane

F. ethyl hexanoate

G. butanal

H. propyne

J. 2,4-dimethyl-pent-2-ene

Explanation:

sorry i didn't have time to do I

Answer:

A. increase

Explanation:

the smaller the size of the ionic compounds, the more closer they get packed together. This means electrostatic attraction also increases, which means the ionic bonds gets stronger...therefore increases the melting point

bcz the defination of matter is that

anything which occupy space

Hence , option a is correct

Answer:

The egg will gain mass.

Explanation:

Eggs soaked in distilled water will gain mass and appear dramatically swollen.

Answer:

Gain mass

Explanation:

Carbonated water will create a reaction inside the egg making the fluid inside the egg becoming more solid thus gaining mass

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Answer:

Vitamins are classified as either fat soluble (vitamins A, D, E and K) or water soluble (vitamins B and C). This difference between the two groups is very important. It determines how each vitamin acts within the body.

Answer:

Place the object in the graduated cylinder, and record the resulting water volume as "b." Subtract the volume of the water alone from the volume of the water plus the object. For instance, if "b" was 50 milliliters and "a" was 25 milliliters, the volume of the irregularly shaped object would be 25 milliliters.

The number of grams of ammonium nitrate (NH₄NO₃) it would take for all the barium hydroxide to react is 18.7g

First, we will write the balanced chemical equation for the reaction

The balanced chemical equation for the reaction is

Ba(OH)₂ + 2NH₄NO₃ → 2NH₄OH + Ba(NO₃)₂

This means, 1 mole of barium hydroxide is required to react with 2 moles of ammonium nitrate

Now, we will calculate the number of moles of barium hydroxide present.

Mass of barium hydroxide (Ba(OH)₂) = 20 g

Using the formula

[tex]Number\ of\ moles = \frac{Mass}{Molar\ mass}[/tex]

Molar mass of Ba(OH)₂ = 171.34 g/mol

∴ Number of moles of Ba(OH)₂ present =[tex]\frac{20}{171.34}[/tex]

Number of moles of Ba(OH)₂ present = 0.116727 mole

Now,

Since 1 mole of barium hydroxide is required to react with 2 moles of ammonium nitrate

Then,

0.116727 mole of barium hydroxide will react with 2 × 0.116727 mole of ammonium nitrate

2 × 0.116727 = 0.233454 mole

∴ Number of moles of NH₄NO₃ required is 0.233454 mole

Now, for the mass of ammonium nitrate (NH₄NO₃) required

From the formula

Mass = Number of moles × Molar mass

Molar mass of NH₄NO₃ = 80.043 g/mol

∴ Mass of NH₄NO₃ required = 0.233454 × 80.043

Mass of NH₄NO₃ required = 18.68636 g

Mass of NH₄NO₃ required ≅ 18.7g

Hence, the number of grams of ammonium nitrate (NH₄NO₃) it would take for all the barium hydroxide to react is 18.7g

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Answer:

When molecular hydrogen (H2) and oxygen (O2) are combined and allowed to react together, energy is released and the molecules of hydrogen and oxygen can combine to form either water or hydrogen peroxide . These two processes are represented by the two chemical equations shown at right.

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