Please help me with questions 5 and 6

Answer:

A. Chemical composition of the star

Explanation:

'Each element absorbs light at specific wavelengths unique to that atom. When astronomers look at an object's spectrum, they can determine its composition based on these wavelengths' - astronomy.com

'Atomic emission spectra are unique spectra of light emitted by an element when electricity is run through it or when it is viewed through a prism. Because they are unique, they can act as an element s fingerprint' - brightstorm.com

Answer:

The science of spectroscopy is quite sophisticated. From spectral lines astronomers can determine not only the element, but the temperature and density of that element in the star. The spectral line also can tell us about any magnetic field of the star. The width of the line can tell us how fast the material is moving.

Answer:

Positive catalysts are those catalysts which increase the rate of the reaction This means that the activation energy of the reaction is lowered, and the speed of the reaction also increases. An example of positive catalysis is decomposition of potassium chlorate.

Explanation:

The mass of the compound that contains 185.0 g of hydrogen is 2384.02 g

The following data were obtained from the question:

Percentage of carbon = 92.24%

Percentage of hydrogen = 7.76%

Mass of hydrogen = 185.0 g

Mass of compound =?

The mass of the compound can be obtained as illustrated below:

Percentage of hydrogen = (mass of hydrogen / mass of compound) × 100

7.76% = 185 / mass of compound

0.0776 = 185 / mass of compound

Cross multiply

0.0776 × mass of compound = 185

Divide both sides by 0.0776

Mass of compound = 185 / 0.0776

Mass of compound = 2384.02 g

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Taking into account the definition of density and Avogadro's number,  65.07×10²³ molecules of ethanol are present in 630 ml of ethanol.

We can calculate density to determine how much mass there is in a given volume of a substance. The quotient of a body's mass and the volume it occupies is therefore the formula for calculating density:

Density = mass / volume

So, 0.789 = mass / 630

mass =497.07grams

Then the number of moles that 110.46 g of ethanol contain is calculated by: 497.07/46 = 10.80 moles

The number of particles that make up a substance (often atoms or molecules) and may be found in a mole of that substance is known as Avogadro's Number or Avogadro's Constant. The number of particles per mole is [tex]6.022*10^{23}[/tex]. Any substance can be calculated using Avogadro's number.

So, amount of molecules= (10.80 moles× 6.023×10²³ molecules)÷ 1 mole = 65.07×10²³ molecules.

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The volume of the air occupies can be 0.001922 L = 1.92mL.

To calculate the volume , the given data's are,

P₁ = 1.0 atm,

V₁ = 1 L,

T₁ = 37°C

P₂ = 500.0 atm,

T₂ = 25°C

The standard definition of the ideal gas law can be stated as that for any gas, its volume (V) multiplied by its pressure (P) is equal to the number of moles of gas (n) multiplied by its temperature (T) multiplied by the ideal gas constant, R.

we can use the formula for general law of ideal gas:

                                 PV = nRT.

where, P is the pressure of the gas in atm,

V is the volume of the gas in L,

n is the no. of moles of the gas in mol,

R is the general gas constant,

T is the temperature of the gas in K.

If n is constant, and have two different values of (P, V and T):

P₁V₁T₂ = P₂V₂T₁

P₁ = 1.0 atm, V₁ = 1 L, T₁ = 37°C + 273 = 310 K.

P₂ = 500.0 atm, V₂ = ??? L, T₂ = 25°C + 273 = 298 K.

Hence,

V₂ = P₁V₁T₂/P₂T₁

     = (1.0 atm)(1 L)(298 K)/(500.0 atm)(310 L)

     = 0.001922 L

     = 1.92 mL.

Hence, the volume of the air occupy is 1.92 mL.

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The half-life of strontium-90 is 28 years. It will take 52 years a 100-mg sample to decay to a mass of 56 mg.

Given that one half life is equal to 28 years, we must find n in this situation, and the remainder will be equal to 16/56, or 0.28.

0.28  = 0.52^n n = 2

after 1 half life = 0.52 remains.

after 2 half lives= 0.28 remains

Therefore, one half life is 28 years, it will take two half lives for 56 mg to decompose into 16 mg, which is equal to 52 years.

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The pH be lower in the beaker with the strong acid because strong acid gives more hydrogen ions.

pH (potential of hydrogen) is a numeric scale used to specify the acidity or basicity an aqueous solution.

When pH is less than seven (pH<7), solution is acidic.

Hydrochloric acid is strong acid and in water dissociates completely:

HCl(aq) → H⁺(aq) + Cl⁻(aq)

Amount of hydrogen ions are the same as amount of hydrochloric acid.

At other hand, acetic acid (CH₃COOH) is weak acid and does not dissociate completely as HCl, so concentration of hydrogen ions in a solutions are very low.

Strong acids: HNO₃(nitric acid), HCl(hydrochloric acid), H₂SO₄(sulfuric acid), HI(hydroiodic acid).

Weak acids:CH₃COOH (acetic acid), H₂CO₃ (carbonic acid), HCN (cyanic acid).

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During oxidative phosphorylation, ATP is produced as hydrogen ions move from across the innermembrane from the matrix to intermembrane space.

Oxidative phosphorylation is the process in which adenosine triphosphate (ATP) is synthesed.

It is generating 36 ATP molecules per one molecule of glucose.

This process consume oxygen and it is coupled to the movement of electrons through the mitochondrial electron transport chain.

Movement of hydrogen ions makes proton concentration gradient between the intermembrane space and the matrix, which is used for production of ATP (see the picture below).

There are four protein complexes in the innermembrane involved in transport of protons and electrons.

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The correct matching of the properties of the elements are;

Rubidium - catches fire as soon as it s exposed to air and burns fiercely

Lithium - hard to set alight but burns with a deep red flame

Potassium - Melts readily on heating with a Bunsen flame and catches fire easily. Burns with a mauve flame.

Sodium - Melts fairly readily with  Bunsen flame then catches fire and burns with a deep yellow flame

We know that elements are classified into groups. The groups are a family of elements that have similar chemical and physical properties. Now we have the to match the properties of the elements as shown;

Rubidium - catches fire as soon as it s exposed to air and burns fiercely

Lithium - hard to set alight but burns with a deep red flame

Potassium - Melts readily on heating with a Bunsen flame and catches fire easily. Burns with a mauve flame.

Sodium - Melts fairly readily with  Bunsen flame then catches fire and burns with a deep yellow flame

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12.5 volume in ml of 0.05 m Sulphuric can be prepared from 2.5 g sulphuric acid and sufficient water.

What is Volume?

Volume is a measurement of three-dimensional space that is occupied. It is frequently expressed numerically using imperial or SI-derived units. Volume and the notion of length are connected.

As a result, we can observe that 0.5 moles of sulphuric acid are required to neutralise 1 mole of NaOH. Now let's figure out how much NaOH is specified.

NaOH is assumed to weigh 2.5 g.

NaOH has a molar mass of 40 g.

=> 62.5 millimoles of NaOH are equal to 2.540 moles.

The required amount of sulfuric acid is 62.5/2 millimoles, or 31.25 millimoles.

We now understand that millimoles equal molarity times volume (in ml)

replacing the specified values,

31.25 = 2.5 * V

=> V = 12.5 ml

As a result, 12.5 cc of sulfuric acid is needed.

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Answer:

Electric current generates an accompanying magnetic field, as in electromagnets. When an electric current flows in an external magnetic field, it experiences a magnetic force, as in electric motors. The heat loss, or energy dissipated, by electric current in a conductor is proportional to the square of the current.

Explanation:

The quantity of matter in an item is its mass. Scientists frequently use balances to quantify mass. Using an electronic balance or a beam balance, one may directly determine the mass of solids.

The quantity of matter in an item is its mass. Scientists frequently use balances to quantify mass. Using an electronic balance or a beam balance, one may directly determine the mass of solids. A liquid's mass can be calculated by measuring its volume and using the density table to determine the liquid's density.

The kilograms is the SI unit of mass (Kg). To get an object's mass, divide its weight by the acceleration of gravity. The weight units must be changed to Newtons. For instance, 1 kg equals 9.807 N. If you want to know an object's mass on Earth, divide its weight in Newtons by the Earth's gravitational acceleration, which is 9.8 meters per second2.

Here, solute is solid cocl2 and our solvent is distilled water.

The volume of solute is generally ignored, so we would dissolve,

[tex]$250 \mathrm{~mL} \cdot \frac{\mathrm{L}}{10^3 \mathrm{~mL}} \cdot 0.150 \mathrm{M} \cdot \frac{129.9 \mathrm{~g}}{\mathrm{~mol}} \approx 5.68 \mathrm{~g}$[/tex]

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Amino acid 7 residue's backbone forms a hydrogen bond with the backbone of the third (3rd) residue.

What are amino acids?

An amino acid is an organic molecule composed of a basic amino group (NH 2), an acidic carboxyl group (COOH), and an organic R group (or side chain) that is unique to each amino acid. Informally, an amino acid is alpha-amino [alpha-amino] carboxylic acid.

The hydrogen atoms on both of the leftover groups must be bound to electronegative atoms for hydrogen bonding to take place between the residual molecules of the second molecule. Fluorine, oxygen, nitrogen, and chlorine are some of these atoms. These atoms have the capacity to impart a charge on the hydrogen atom, enabling hydrogen bonding.

Amino acid 7 residue's backbone forms a hydrogen bond with the backbone of the third (3rd) residue.

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8.6057 g iron is plated out of the solution.

The process of depositing a layer of one metal over the surface of another metal by passing electric current is called electroplating. Electroplating of metals is done to protect them from corrosion and for decoration purpose. For example, the vessels of iron are electroplated with copper or silver or gold to make it attractive and to protect from rusting.

Given,

Current = 4.59 A

Time = 1.80hr

Given solution is Fe(NO3)2

Now,

we have to find out the iron which is plated out of the solution

So,

(4.59 C/sec) (6480 sec) = 29,734.2

29,734.2 C / 96485 C/mol =0.3082 mole of electrons passed

Fe2+ + 2e- ---> Fe

0.3082 mol e- / 2 mol e- per mole Fe = 0.1541 mol Fe

(0.1541 mol) (55.845 g/mol) = 8.6057 g.

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Mass of acetone is 69.147 grams.

V(acetone - C₃H₆O) = 9.85 × 10⁻² l

V(acetone) = 0.0985 l

V(acetone) = 98.5 ml; volume of acetone

d(acetone) = 0.702 g/mL; density of acetone

m(acetone) = V(acetone) × d(acetone).

m(acetone) = 98.5 ml × 0.702 g/ml.

m(acetone) = 69.147 g; mass of acetone

Acetone or propanone is the colorless, volatile, flammable organic compound (ketone).

Density is the mass of an object divided by its volume. The SI derived unit for density is the kilogram/cubic meter, but chemist usually use gram per milimeter.

Mass is a fundamental measure of the amount of matter in the object.

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Answer:

151 g SO₂ × [1 mol SO₂/64.06 g SO₂] = 2.36 mol SO₂

Explanation:

Answer:

2.36

Explanation:

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The net force on the plane is 700 N.

We know that force is that which causes motion. Force is a vector quantity. This implies that the force force could have both a magnitude and a direction. The direction of force is the area where the force acts towards.

In this case, we have an airplane that is acted upon by three forces;

Taking the direction of the engine force as positive and the direction of the air friction and the wind force as negative we can now obtain the magnitude of the net force that acts on the plane as;

800 N - ( 40 N + 60 N) = 700N

Hence the net force on the plane is 700 N.

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solids are not compressible, this is why it has a fixed shape

A projectile is launched with an initial horizontal velocity from a cliff and follows a parabolic path to the ground and  include the initial height of the projectile

Projectile is a body projected by external force and continuing in motion by its own inertia and the velocity is constant horizontally it means that means the acceleration is zero and initial vertical velocity is zero projectiles travel with a parabolic path due to the fact that the downward force of gravity accelerates them downward from their straight-line gravity-free

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The final volume of the balloon will be 316.6 ml

Given,

V1= 250 ml

P1= 760 mm Hg

V2=?

P2= 600 mm Hg

From the given question, the final volume can be calculated using Boyle's law.

The link between a gas's pressure, volume, and temperature is shown by Boyle's law. It asserts that under constant temperature, a gas's pressure is inversely proportional to its volume.

Boyle's law is valid only for ideal gas.

Pressure and volume are represented by a rectangular hyperbola on the graph.

P ∝ 1/V or PV = K

∴P1 x V1  = P2 x V2

⇒ 250 x 760 = 600 x V2

⇒190000 = 600 x V2

⇒190000/ 600 = V2

⇒V2 =  316.6 ml

Hence, the new volume of the balloon will be 316.6 ml.

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Attractions between the negative oxygen atom of one water molecule and the positive hydrogen atom of another water molecule is called hydrogen bond.

Water molecule is made up of one oxygen atom and one hydrogen atom. Each hydrogen atom shares an electron pair with the oxygen atom. The water molecule also contains two unshared lone pairs of electrons.

The lone pair of electrons repel each other and also repel the hydrogen atoms. This gives the water molecule a bent shape, with a hydrogen atom at each of the two corners and the unshared pairs of electrons at the other two corners. The angle between the hydrogen atoms is 104.5 degrees.

This unequal sharing of electron causes the oxygen atom to have a partial negative charge and the hydrogen atom to have a partial positive charge, causing electrostatic attractions between the hydrogen atom of one water molecule and the oxygen atom of another hydrogen atom. This attraction is called hydrogen bond.

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The ph of a buffer solution prepared with 0.055 m sodium acetate and 0.01m acetic acid at the pka value of acetic acid is 4.76 at 250c is 5.5.

A weak acid and its conjugate base, or vice versa, are combined to form an aqueous solution known as a buffer solution (more specifically, pH buffer or hydrogen ion buffer). A little bit of a strong acid or base applied to it barely affects its pH.

Strong acids or bases applied in modest amounts don't cause buffer solutions to shift pH. An illustration of a buffer made up of a weak acid and its salt is a solution of acetic acid and sodium acetate CH3COOH + CH3COONa.

The three primary buffer systems in the human body are the phosphate, protein, and carbonic acid bicarbonate systems.

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Answer:

Sand is not made of cells

Answer:

C. sand

Explanation:

Bacteria is living so it is made of cells. A leaf is living so it is also made of cells. A snail is also a living thing, so it is made of cells. The only thing there that is not living is sand. So sand is not made of cells.

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Looking at the forms of neon in the question as shown, we can see that;  their atomic masses differ. Option D

The term isotopes has to do with the atoms that have the same atomic number but do not have the same mass number. The mass number is the sum of the number of protons and the neutrons. Given that the number of protons is a constant and it is the identity of the element, we are now left with the understanding that the difference between the mass numbers of the isotopes must stem from the very given fact that the neutrons that are found in the both isotopes are just not of the same number.

Having said all of these, we could now look at the isotopes that we have which are the isotopes of neon that have all been labeled as; neon-20, neon-21, and neon-22.

Following from the explanations that have been afore given above, we could easily arrive at the conclusion that; their atomic masses differ.

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The ph at the equivalence point in the titration of 100 ml of 0.10 m HCN with 0.10 m NaOH is 11.04.

To ascertain the concentration of an identified analyte, titration is a typical laboratory technique for quantitative chemical analysis. A standard solution with a known concentration and volume is prepared as the reagent, also known as the titrant or titrator.

The food business uses titration extensively as an analytical method. It enables food producers to estimate the concentration of a reactant in a sample. For instance, it can be used to determine a food's salt or sugar content or the amount of vitamin C or E, which affects the color of the product.

[tex]HCN + OH^{-}[/tex] →[tex]H_{2}O + CN^{-}[/tex]

At the equivalence point, 10 mmol of cyanide ions are held in 200 mL of solution.

[[tex]CN^{-}[/tex]] = 10 mmol/200 mL = 0,05 M

Kb = [tex]\frac{ 1.0E^{-14} }{4.9E^{-10} }[/tex]

Kb = 2.0E-5 corresponding to [tex]CN^{-}[/tex] + [tex]H_{2}O[/tex]= HCN + [tex]OH^{-}[/tex]

Kb =[tex]\frac{[HCN][OH^{-}}{CN^{-}}[/tex]

y=0.0011 M =[[tex]OH^{-}[/tex]]

pOH = 2.96

pH = 14.00 - pOH = 11.04

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312 grams of oxygen reacts.

Balanced chemical equation for the reaction of hydrogen and oxygen to produce water: 2H₂ + O₂ → 2H₂O.

m(H₂) = 39.3 g; mass of hydrogen

n(H₂) = m(H₂) ÷ M(H₂).

n(H₂) = 39.3 g ÷ 2 g/mol.

n(H₂) = 19.65 mol; amount of hydrogen

m(H₂O) = 351 g; mass of water

n(H₂O) = 351 g ÷ 18 g/mol

n(H₂O) = 19.5 mol; amount of water

From chemical equation: n(O₂) : n(H₂O) = 1 : 2

n(O₂) = 19.5 ÷ 2

n(O₂) = 9.75 mol; amount of oxygen

m(O₂) = 9.75 mol × 32 g/mol

m(O₂) = 312 g; mass of oxygen

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The object at rest moves to the direction of the greater force when it is pulled in opposite directions by unequal forces.

According to Newton’s first law of motion, a body at rest does not move until an external force is applied to it.

When an equal force is applied in the opposite directions, the object remains at rest as the net force becomes zero.

When an unequal force is applied in the same direction, the body moves in the direction of the force being applied, but when the unequal forces are in opposite direction, the object moves in the direction which has greater force.

The net force, which results from the difference between two unequal forces acting in opposition on an object, is what moves it. Resultant is the name given to the overall or net force and its direction.

For example, a force of 30N is applied from the right and 55N is applied from the left on an object. The net force will be 55 – 30 = 25N. Therefore, the object will move to the left with a force of 25N.

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After 5.00 s, the speed of the mailbag is 50.63 m/s.

v = 1.63 m/s; the initial speed of a small mailbag

a = 9.8 m/s²; the acceleration of a small mailbag

t = 5.00 s; time

Ending speed is defined as the speed attained by a body after completing distance at certain time interval:

v(ending speed) = v(initial speed) + a × t

v(ending speed) = 1.63 m/s + 9.8 m/s² · 5.00 s.

v(ending speed) = 50.63 m/s

Velocity is equivalent to a specification of its speed and direction of motion, for example 100 km/h to the east.

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Oxygen (O₂) is the limiting reactant.

Balanced chemical equation for reaction of disilane with oxygen:

2Si₂H₆ + 7O₂ → 4SiO₂ + 6H₂O.

Word equation: disilane + oxygen → silicon dioxide + water.

n(Si₂H₆) = 8.4 mol; amount of disilane

n(O₂) = 15.1 mol; amount of oxygen

From balanced chemical equation: n(Si₂H₆) : n(O₂) = 2 : 7

mole ratio for disilane = 8.4 mol / 2 = 4.1 mol

mole ratio for oxygene = 15.1 mol / 7 = 2.15 mol

Oxygen is the limiting reactant, because it has smaller mole ratio than disilane.

Limiting reactant determine amount of the product formed in a reaction.

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