Solve the following and express each answer in scientific notation and to the correct number of significant figures.
A). (5.3 x 10^4) + (1.3 x 10^4)
B). (7.2 x 10^-4) /(1.8 x 10^3
C). 10^4 x 10^-3 x 10^6
D). (9.12 x 10^-1) - (4.7 x10^-2
E). (5.4 x 10^4) x (3.5 x 10^9)

The molar mass of PCl5 is 208.24 g/mol. So calculating for the number of moles:

moles PCl5 = 280 / 208.24

moles PCl5 = 1.34 mol

From the equation, 67 kJ of heat is absorbed for every 1 mole hence:

total heat = 67 kJ / mol * 1.34 mol

total heat = 90 kJ

Among the given substances, Ammonia, a compound, can be decomposed into Nitrogen and Hydrogen by a chemical change.

The substance that can be decomposed by a chemical change among Sodium, Argon, Sulfur, and Ammonia is Ammonia. In a chemical change, one or more substances are converted into different substances. In this context, Sodium, Argon, and Sulfur are elements that exist in their most simplified form and cannot be broken further down by chemical change. On the other hand, Ammonia (NH3) is a compound and can be decomposed into Nitrogen and Hydrogen via chemical changes.

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Answer: The energy associated with blue light is [tex]49.65\times 10^{-20}J[/tex]

Explanation:

To calculate the energy of the light for a given frequency, we use the equation given by Planck, which is:

[tex]E=h\nu[/tex]

where,

E = energy of the light

h = Planck's constant = [tex]6.62\times 10^{-34}Js[/tex]

[tex]\nu[/tex] = frequency of the light = [tex]7.5\times 10^{14}s^{-1}[/tex]

Putting values in above equation, we get:

[tex]E=6.62\times 10^{-34}Js\times 7.5\times 10^{14}s^{-1}=49.65\times 10^{-20}J[/tex]

Hence, the energy associated with blue light is [tex]49.65\times 10^{-20}J[/tex]

[tex]\rm 49.65 \times 10^-^2^0\;J[/tex] is the energy associated with the frequency.

The number of times a repeated event occurs per unit of time is known as frequency.

The frequency of the blue light is 7.5 x 1014 Hz

To calculate the energy of the light, we will use plank's equation

[tex]\rm E = hv[/tex]

Where E = energy

[tex]\rm Plank's \;constant = 6.62 \times 10^-^3^4 Js\\\\ Frequency \;of \;the\;light\;v = 7.5 \times 10^-^1^4 s^-^1[/tex]

Putting the values

[tex]\rm E =6.62 \times 10^-^3^4 \times 7.5 \times 10^-^1^4 = 49.65 \times 10^-^2^0\;J[/tex]

Thus, the energy associated with this frequency is [tex]\rm 49.65 \times 10^-^2^0\;J[/tex]

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Answer:

A.fluorine

Explanation:

Plato

Rutherford deduced that an atom is mostly empty space because most alpha particles in his experiment passed through the gold foil unabated; only a few particles deflected due to the presence of a small, dense, positively charged nucleus.

Rutherford concluded that the atom was mostly empty space based on his gold foil experiment. He observed that the vast majority of the alpha particles passed through the gold foil without deflection, indicating that they encountered no significant obstacle, hence most of the atom was empty space. A very small number of alpha particles were deflected at large angles, and even fewer were deflected straight back, which suggested that they interacted with something very small and with a substantial positive charge and mass. This led Rutherford to propose the nucleus, a tiny, dense center within the atom composed of protons and neutrons. He surmised that the electrons orbit this nucleus, much like planets around the sun, in what is known as the planetary model of the atom.

The lead piece has more mass with a mass of 319.2 g, while the gold piece has a mass of 308.8 g.

To determine which piece has more mass, we need to calculate the mass of each piece using the given densities.

The mass of an object can be calculated using the formula:

mass = density x volume

For the lead piece:

mass of lead = density of lead x volume of lead

mass of lead = 11.4 g/cm3 x 28.0 cm3

mass of lead = 319.2 g

For the gold piece:

mass of gold = density of gold x volume of gold

mass of gold = 19.3 g/cm3 x 16.0 cm3

mass of gold = 308.8 g

Comparing the masses of the two pieces, we can see that the lead piece has more mass with a mass of 319.2 g, while the gold piece has a mass of 308.8 g.

Answer:

The second step is the atomization (sublimation) of Ba

Ba(s) → Ba(g)

Explanation:

The Born Haber cycle allows one to determine the lattice energy of an ionic solid. Lattice energy or lattice enthalpy is the enthalpy change when 1  mole of an ionic solid is formed from its gaseous ions.

In the given example of BaI2 the corresponding steps as per the Born Haber cycle would be:

Step 1) Enthalpy of Formation of BaI2

Ba(s) + I2(s) → BaI2 (s)

Step 2) Atomization of Ba

Ba(s) → Ba(g)

Step 3) Atomization of I2

I2(s) → I2(g)

Step4) IOnization of Ba(g)

Ba(g) → Ba2+(g) + 2e-

Step 5) Electron affinity of I2

I2(g) + 2e- → 2I-(g)

Step 4) Lattice energy of BaI2

Ba2+ (g) + 2I-(g) → BaI2

1. Speed, since we know that [tex]s=\frac{d}{t}[/tex], where s is speed, d is distance and t is time

2. Velocity, for velocity you need to consider the direction and displacement gives the direction of travel.

3. 25 mph, because [tex]s=\frac{d}{t} =\frac{50}{2} =25mph[/tex]

4. 50 mph east, velocity unlike speed has direction.

5.Velocity, displacement gives the formula  [tex] v=\frac{d}{t}[/tex] direction.

6. 0, the displacement is zero so velocity is zero

7.  It decreases, speed is inversely proportional to time

The balanced equation with the reaction-quotient expression is;

U(s) + 3F₂(g) → UF₆(g)

Keywords: Chemical equations, balancing of chemical equations

Level: high school  

Subject: Chemistry  

Topic: Chemical equations

Sub-topic: Balancing chemical equations  

The balanced chemical equation is U(s) + [tex]3F_2[/tex](g) → [tex]UF_6[/tex](g), and the reaction-quotient expression is Qc = [[tex]UF_6[/tex]] /[tex][F_2]^3[/tex].

To balance the chemical reaction and write the reaction-quotient expression (Qc) for the equation U(s) + [tex]F_2[/tex] (g) → [tex]UF_6[/tex] (g), let's follow these steps:

Step 1: Balance the Chemical Equation

U(s) + [tex]F_2[/tex] (g) → [tex]UF_6[/tex] (g)

U(s) + [tex]3F_2[/tex] (g) → [tex]UF_6[/tex] (g)

Step 2: Write the Reaction-Quotient Expression, Qc

Qc = [[tex]UF_6[/tex]] / [tex][F_2]^3[/tex]

After balancing the equation, U(s) + [tex]3F_2[/tex](g) → [tex]UF_6[/tex](g), the reaction-quotient expression is Qc = [[tex]UF_6[/tex]] / [tex][F_2]^3[/tex]. This helps assess the direction of the reaction to reach equilibrium in a given system.

Among the following, Li will form Catian due to its high probability of donating electron as it have low ionization enthalpy.

The ionization enthalpy of an element can be defined as the amount of energy required to remove an electron from an isolated gaseous atom in its gaseous state.

Among th given options ;

Ne is an inert gas element i.e, inactive element and has complete outermost orbit thus no need to accept or donate electron.

Li will form Catian due to its high probability of donating electron as it have low ionization enthalpy.

O has stable outermost orbital and thus no need to accept or donate electron.

I is the least reactive element and comparatively high ionization enthalpy.

Hence, Among the following, Li will form Catian due to its high probability of donating electron as it have low ionization enthalpy.

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Answer: It is considered to be a mixture

Explanation: It's a mixture because the mud and water are mixed together, which will create a mixture.

It would be a heterogeneous mixture because the mud and water are not mixed evenly, and a heterogeneous mixture is a mixture that is not mixed evenly, whereas a homogeneous mixture is something that is mixed evenly:)

Final answer:

Atoms of an element are identical in atomic structure but can include different isotopes. Samples of beryllium and carbon can contain isotopes, but most atoms will be of the most common isotope. The presence of atoms with a mass number greater than 12 in a carbon sample indicates isotopes like carbon-13 or carbon-14.

Explanation:

If you have a sample of beryllium, the atoms within that sample would be identical in terms of their atomic structure, meaning each atom has the same number of protons, neutrons, and electrons. However, any sample of an element, including beryllium and carbon, can contain different isotopes, which means there can be atoms with different numbers of neutrons. For example, the most prevalent isotope of carbon is carbon-12, with 6 protons and 6 neutrons. In addition to carbon-12, we also find carbon-13, with an extra neutron, and carbon-14, with two extra neutrons.

When you analyze a sample of carbon and find that 6% of the atoms have a mass number greater than 12, you can conclude that 6% of the sample is comprised of carbon isotopes. This means the vast majority (94%) of your sample is carbon-12, the normal atomic mass of carbon, while the remaining part consists of isotopes like carbon-13 and the radioactive carbon-14. Carbon-14 is used in radiocarbon dating, a tool for archaeological studies.

the correct answer is 2,3,4,6, and 7

Answer:

the states of the reactants and products

the temperature and pressure at which the reaction was carried out

the relative amounts of reactants and products

the type of catalyst that is used to speed up the reaction

whether the reaction can go in both directions

2, 3, 4, 6, 7 / B, C, D, F, G

Answer is: No. Salt, like all matter is composed of atoms.

For example, table salt is sodium chloride mixed with small amount of potassium iodide (KI), sodium iodide (NaI) or sodium iodate (NaIO₃).

Atomic level - sodium chloride (NaCl) has crystal cubic structure (lattice-type arrangement) with ionic bonds. Sodium is cation with charge 1+ and chlorine is an anion with charge 1-.

Macroscopic level - table salt is colorless crystal, soluble in water with high melting and boiling temperature.

Answer: The correct answer is chemical reactivity of metals increases.

Explanation:

Chemical reactivity is defined as the tendency of an element to loose of gain electrons.

Metals are the elements which looses electrons and hence, their chemical reactivity will be the tendency to loose electrons. Their chemical reactivity increases as we move from top to bottom in a group. This is so because, the electron get added up in the new shell. So, the electron in the outermost orbital gets far away from the nucleus. And hence, this will be lost easily. Thus, the chemical reactivity gets increases.

Non-metals are the elements which gains electrons and hence, their chemical reactivity will be the tendency to loose electrons. Their chemical reactivity decreases as we move from top to bottom in a group. As, the electrons get added up in the new shell. So, the the electron in the outermost orbital gets far away from the nucleus. And hence, the electron will be difficult to gain. Thus, the chemical reactivity of non-metals decreases.

Hence, the correct answer is chemical reactivity of metals increases.

Answer:

The answer in b

Explanation:

Because if she falls the momentum pushes him/her.

I hope this helped! :)

Answer : The [tex]\angle 3\text{ and }\angle 4[/tex] are, supplementary angles.

Explanation :

Supplementary angles  : The two angles are supplementary angle in whcih the the sum of those two angle are [tex]180^o[/tex]

Complementary angles  : The two angles are complementary angle in whcih the the sum of those two angle are [tex]90^o[/tex]

Vertical angles  : Vertical angles are the angles that are opposite to each other when two lines intersect each other.

Congruent angle : It is defined as they have the same angles.

From the above information we conclude that,

[tex]\angle 1\text{ and }\angle 2[/tex], [tex]\angle 2\text{ and }\angle 3[/tex], [tex]\angle 3\text{ and }\angle 4[/tex] and [tex]\angle 4\text{ and }\angle 1[/tex] are the supplementary angles.

[tex]\angle 1\text{ and }\angle 3[/tex] and [tex]\angle 2\text{ and }\angle 4[/tex] are the vertical angles.

Hence, the [tex]\angle 3\text{ and }\angle 4[/tex] are, supplementary angles.

Answer:

H2

Explanation:

The 2 in this equation is supposed to be little.