Which of the following can cause a population to decrease in size?
A Lack of rain
B. More births than deaths C. Plentiful food supplies
D. Organisms moving into an area, but not out.

Answer:

Valency can be defined as a measure of the combining power of a chemical element with other atoms to form a molecule or chemical compound.

Explanation:

An atom can be defined as the smallest unit comprising of matter that forms all chemical elements. Thus, atoms are basically the building blocks of matters and as such determines or defines the structure of a chemical element.

Generally, atoms are typically made up of three distinct particles and these are protons, neutrons and electrons.

In Chemistry, electrons can be defined as subatomic particles that are negatively charged and as such has a magnitude of -1.

Valence electrons can be defined as the number of electrons present in the outermost shell of an atom. Valence electrons are used to determine whether an atom or group of elements found in a periodic table can bond with others. Thus, this property is typically used to determine the chemical properties of elements.

Valency can be defined as a measure of the combining power of a chemical element with other atoms to form a molecule or chemical compound.

Typically, valency is measured by the amount of hydrogen atoms that a chemical element can combine with or displace to form a molecule or chemical compound.

For example, Oxygen has a total number of eight (8) electrons while neon has total number of ten (10) electrons. Therefore, an atom of oxygen is able to gain (accept or receive) two (2) more electrons in order to have the same electron arrangements as the noble gas i.e an atom of neon with an atomic number of 10.

Answer:

Oxygen is the nearest noble gas

Answer:

b

Explanation:

The chemical formula for a compound between Rb and the nitrate ion NO₃-1 is Rb(NO₃)₂. Hence, option B is correct.

Chemical formulas can be written for elements, compounds, and molecules. A compound is a substance made up of two or more different elements in a fixed ratio, and its formula shows the types of atoms and the number of each atom in the compound.

Rb(NO₃)₂ is the chemical formula for rubidium nitrate. It is an ionic compound composed of one rubidium cation (Rb+) and two nitrate anions (NO₃-) held together by ionic bonds.

The Rb+ ion has a charge of +1 and the NO₃- ion has a charge of -1, so two nitrate ions are needed to balance the charge of one rubidium ion. The overall charge of the compound is neutral.

Thus, option B is correct.

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Answer:

The correct answer is - may not be typical, and participant burden.

Explanation:

The 24-hour recall is nothing but a retrospective method of diet assessment. In this method, an individual is interviewed about his or her diet consumption during the last 24 hours.

The disadvantages or limitations of this method include the inability of a single day's intake to describe the typical diet, multiple recalls to intake, cost and administration time; participant burden, have to recall to reliably estimate usual intake.

Carbon has an atomic number of 6 so its electron configuration will be 1s² 2s² 2p². It has two orbitals as indicated with the 2 as its period number with the outer orbital have 4 valence electrons. So carbon is in the p-orbital, period 2 and in group 4.

So, the molar mass of tetraethyl lead is

[tex]207.2+8(12.011)+20(1.00794)=\boxed{323.4468 \text{ g/mol}}[/tex]

Answer:

B

Explanation:

A chemical reaction equation is balanced if the number of atoms of each element on the right hand side of the reaction equation is the same as the number of atoms of the same element on the left hand side of the reaction equation.

By inspection, the chemical reaction written in the question is a balanced chemical reaction equation.

However, the statement in option B that more molecules of N2 are needed to produce NH3 than molecules of H2 is a false statement since only one mole of N2 and three moles of H2 are required to produce NH3 according to the reaction equation as written in the question.

Answer:

A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur.

Explanation:

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Answer:

1.586x10^-9

Explanation:

To make a multiplication in scientific notation we need to multiply the coefficients and sum the exponents:

Coefficients: 2.600 * 6.1000 = 15.86

Exponents: -5 + (-5) = -10

The result is:

15.86x10^-10

As the scientific notation must be given with only 1 number in the left of the point:

Answer:

The correct answer is - Statement I is true, Statement-II is false.

Explanation:

Answer:

333g/L

Explanation:

The moles of CaCl2 in 6mEq are:

6mEq * (1mmol / 2mEq) = 3mmol CaCl2.

2Eq / mol because the charge of Ca is 2+

The mass is:

3mmol CaCl2 * (111mg/mmol) = 333mg = 0.333g

Molar mass: 2*35.5g/mol + 40g/mol = 111g/mol = 111mg/mmol

The liters are:

1mL * (1L / 1000mL) = 1x10⁻³L

The concentration in grams per liter is:

0.333g / 1x10⁻³L = 333g/L

Answer: Chromatography is a technique for the separation of a mixture. The mixture is dissolved in a fluid (gas, solvent, water, ...) called the mobile phase, which moves it through a system (a column, a capillary tube, a plate, or a sheet) on which is fixed a material called the stationary phase.

Explanation:

Answer:

Hey there

Explanation:

The process where organisms better adapted to their environment tend to survive and produce more offspring is called natural selection. It is one of the points of Darwinism by Charles Darwin.

Hope it helps

Respuesta:

Cr₂S₃O₁₂

Explicación:

Primer paso: Dividir el porcentaje en masa de cada elemento por su masa atómica

Cr: 26,53/52 = 0,510

S: 24,52/32 = 0,766

O: 48,96/16 = 3,06

Segundo paso: Dividir todos los números por el más pequeño (0,510)

Cr: 0,510/0,510 = 1

S: 0,766/0,510 = 1,5

O: 3,06/0,510 = 6

Tercer paso: Multiplicar todos los números por algún número que haga que todos sean enteros (2)

Cr: 1 × 2 = 2

S: 1,5 × 2 = 3

O: 6 × 2 = 12

La fórmula empírica es Cr₂S₃O₁₂.

Answer: The empirical formula of the compound becomes [tex]Cr_2S_3O_{12}[/tex]

Explanation:

The empirical formula is the chemical formula of the simplest ratio of the number of atoms of each element present in a compound.

Let the mass of the compound be 100 g

Given values:

% of Cr = 26.53%

% of S = 24.52%

% of O = 48.96%

Mass of Cr = 26.53 g

Mass of S = 24.52 g

Mass of O = 48.96 g

The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)

To formulate the empirical formula, we need to follow some steps:

Molar mass of Cr = 52 g/mol

Molar mass of S = 32 g/mol

Molar mass of O = 16 g/mol

Putting values in equation 1, we get:

[tex]\text{Moles of Cr}=\frac{26.53g}{52g/mol}=0.510 mol[/tex]

[tex]\text{Moles of S}=\frac{24.52g}{32g/mol}=0.766 mol[/tex]

[tex]\text{Moles of O}=\frac{48.96g}{16g/mol}=3.06 mol[/tex]

Calculating the mole fraction of each element by dividing the calculated moles by the least calculated number of moles that is 0.510 moles

[tex]\text{Mole fraction of Cr}=\frac{0.510}{0.510}=1[/tex]

[tex]\text{Mole fraction of S}=\frac{0.766}{0.510}=1.5[/tex]

[tex]\text{Mole fraction of O}=\frac{3.06}{0.510}=6[/tex]

Multiplying the mole fraction of all the elements by 2, in order to make it as a whole number

[tex]\text{Mole fraction of Cr}=(2\times 1)=2[/tex]

[tex]\text{Mole fraction of S}=(2\times 1.5)=3[/tex]

[tex]\text{Mole fraction of O}=(2\times 6)=12[/tex]

The ratio of Cr : S : O = 2 : 3 : 12

Hence, the empirical formula of the compound becomes [tex]Cr_2S_3O_{12}[/tex]

Answer:

okay no problem I will be there

Answer:

See explanation

Explanation:

9g of water contains : 9g/18 g/mol = 0.5 mole of water

1) 2 moles of hydrogen yields 2 moles of water

x moles of hydrogen yields 0.5 moles of water

x= 2 × 0.5/2 = 0.5 moles of hydrogen

Mass of hydrogen = 0.5 moles × 2 = 1 g of hydrogen

2) Number of moles of Al(OH)3 = 468 g/ 78 g/mol = 6 moles

2 moles of Al(OH)3 yields 3 moles of H2O

6 moles of Al(OH)3 yields 6 × 3/2 = 9 moles of H20

Mass of water =9 moles × 18 g/mol = 162 g of water

3) There are 13 oxygen atoms in the compound.

Mass of each oxygen atom = 16 g

Total mass of oxygen atoms = 13 × 16 = 208 g

Answer:

44.8 L

Explanation:

Using the ideal gas law equation:

PV = nRT

Where;

P = pressure (atm)

V = volume (L)

n = number of moles (mol)

R = gas law constant (0.0821 Latm/molK)

T = temperature (K)

At Standard temperature and pressure (STP);

P = 1 atm

T = 273K

Hence, when n = 2moles, the volume of the gas is:

Using PV = nRT

1 × V = 2 × 0.0821 × 273

V = 44.83

V = 44.8 L

Answer:

44.8L

Explanation:

Answer: protein bar,it gives alot of energy and wont upset your stomach!!

Answer:

A) Q + XZ = X + QZ is a single displacement reaction.

B) Q + Z = QZ is a synthesis reaction

C) QT = Q + T is a decomposition reaction

D) QT + XZ = QZ + XT is double replacement reaction.

Explanation:

A) Q + XZ = X + QZ

This is a single displacement reaction because it is one in which one element is substituted for another one in a compound. In this case X is substituted for Q.

B) Q + Z = QZ

This is a synthesis reaction because Q and z combine to form a single product QZ.

C) QT = Q + T

This is a decomposition reaction because the compound QT breaks down to form 2 simpler substances Q and T.

D) QT + XZ = QZ + XT

Thus is a double replacement reaction because QT and XZ have exchanged cations to form new compounds QZ and XT

Answer:

16.7 %(m/m)

Explanation:

The percent by mass of a solution (% m/m) is defined as 100 times the ratio of the mass of solute (The substance in the lower amount, NaCl) and the mass of the solution = Mass solute + Mass Solvent (water).

Mass Solution:

100g NaCl + 500g water = 600g solution

Mass Percent:

100g NaCl / 600g solution * 100

= 16.7 %(m/m)

Answer:

See explanation

Explanation:

The can chiller has a cooling system which expels heat around the immediate vicinity of the can chiller.

Let us remember that convection is a mode of heat transfer that occurs as a result of the actual movement of the particles of a substance. In this case, we are going to consider the movement of air molecules.

As the can chiller expels heat, the air molecules around the can chiller become heated and less dense and begin to move away from the can chiller. They are quickly replaced by cold denser air.

This process of cycling of hot/cold air molecules is known as a convection current. It is set up as a result of the working of the can chiller.

Answer:

bronze, copper

Explanation:

bronze is used to make medals and carve statues

copper is used to make wire and utensils

Answer:

Thompson's experiments with cathode ray tube showed that every atom contains a small amount of negatively charged subatomic particles. Thomson proposed the plum pudding model of the atom.

Explanation:

Answer:

The Magician who lives in sand is called sand witch.

And sandwich is The name of one kind of food.

Answer:

Sandwich its food you eat it

Explanation:

Answer:

80÷4=20 Helium atoms

Explanation:

Because one helium atom is a quarter of of one bromine atom

Answer:

3.98dm³

Explanation:

Using combined gas law equation:

P1V1/T1 = P2V2/T2

Where;

P1 = initial pressure (kPa)

P2 = final pressure (kPa)

V1 = initial volume (dm³)

V2 = final volume (dm³)

T1 = initial temperature (K)

T2 = final temperature (K)

According to the provided information in this question:

V1 = 3.5dm³

V2 = ?

P1 = 101 kPa

P2 = 85.0 kPa

T1 = 23.0°C = 23 + 273 = 296K

T2 = 10.0°C = 10 + 273 = 283K

Using P1V1/T1 = P2V2/T2

101 × 3.5/296 = 85 × V2/283

353.5/296 = 85V2/283

Cross multiply

296 × 85V2 = 353.5 × 283

25,160V2 = 100,040.5

V2 = 100,040.5 ÷ 25,160

V2 = 3.98dm³