Find all solutions in the interval [0, 2π).

7 tan3x - 21 tan x = 0

The mass of platinum taken here is 338.9 g. The mass of one mole of platinum is 195 g. Then , number of moles in 338.9 g is 1.73.

Platinum is 78th element in periodic table. It is a transition metal in d -block. Platinum is a precious metal used in making of ornaments, electrical devices etc.

volume Pt = 15.8 cm³

density = 21.4 g/ cm³

mass = volume × density = 338.9 g.

Atomic mass of platinum = 195 g/mol.

The mass of one mole of platinum metal is 195 g. Then the number of moles in 338.9 g can be calculated as follows:

no.of moles = weight/ atomic mass

n = 338.9 g / 195 g/mol

  = 1.73 moles.

Therefore the number of moles of Pt is 1.73.

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The moles of [tex]\rm Cl_2[/tex] needed to have stoichiometrically equivalent amounts of Na and [tex]\rm Cl_2[/tex] is 1.5 moles.

Stoichiometrically equivalent is defined as a definite quantity of one substances reacted with the definite quantity of other substances represented in the equation.  

It can also be defined as the relationship between the quantities of reactant and product before, during and following equation.

The ratio of [tex]\rm NaCl_2[/tex] is 1:2 because in [tex]\rm NaCl_2[/tex] there is only one mole Na ion is present and 2 mole of Cl ion is present.

Thus moles of Na present = 3 moles

So, 2 / 1 = 3 / x

     x = 3 / 2

     x = 1.5 moles

Thus, the moles of [tex]\rm Cl_2[/tex]needed to have stoichiometrically equivalent amounts of Na and[tex]\rm Cl_2[/tex] is 1.5 moles.

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Silicon dioxide (SiO₂), also known as silica, is a non-polar molecule.

A non-polar molecule is a molecule that has an even distribution of electrical charge, meaning it does not have a positive or negative end.

The molecule's geometry and symmetry lead to its non-polar nature. SiO₂ consists of one silicon atom bonded to two oxygen atoms, forming a linear structure. The oxygen atoms are positioned on opposite sides of the silicon atom, resulting in a symmetric arrangement.

As a result, the bond dipoles cancel each other out, resulting in a non-polar molecule overall.

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Answer: 12 electrons

Explanation:

As the electrons move around the atom, they can move in any direction as long as they stay in their shell, and they are also constantly spinning. Shells or orbitals are specific distances from the nucleus and they are energy levels. Each of those shells has a name and there are a many ways that atomic shells are described.

First, the basic regions where electrons are found which is described using an "n" value, or the letters K, L, M, N, O, P, and Q. The "K" shell is the one closest to the nucleus, and "Q" is the farthest away. The second description looks at how electrons act inside of the shells, described with the "l" value which indicates in which suborbital an electron is found in (s, p, d, f, g, and h)

Quantum numbers are numbers associated with physical quantities conserved in certain quantum systems. 

So, L refers to the s subshell, so L=0 is related with the S-subshell. Ba is an atom found in the 6th shell, and it has the electronic configuration of [Xe]6s2 (1s2s2p3s3p4s3d4p5s4d5p6s), so there would be .12 electrons there because there are 6 s-orbitals with 2 electrons each. On the other hand, ml values rage from -L to L, and since the L value from this question is 0, there are no electrons that have both values of L=0 and ml=1. Since only one orbital of each type can have this magnetic quantum number and each orbital can host 2 electrons, we also have 12 electrons fitting this description.  

In the given question, Gamma rays consist of pure energy. The correct answer is option B.

Gamma rays are electromagnetic radiation with very high frequency and short wavelength.

They have no mass or charge, and are not considered particles like electrons, protons, or beta particles. Gamma rays are produced by the decay of atomic nuclei and are often associated with nuclear reactions such as those that occur in the sun, in nuclear power plants, or in nuclear weapons.

Therefore, Gamma rays are option B. "pure energy" in the form of electromagnetic radiation with an extremely high frequency and short wavelength.

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Answer:

End point.

Explanation:

The end point is the point at which the indicator changes color in a titration.

The end point generally lags behind the neutralization point in a reaction where we have taken acidic or basic indicator.

Indicators show a change or appearance in color at particular pH. This pH is achieved after point of neutralization. However for some indicators the change in color can also be observed at point of neutralization or completion of reaction exactly. In that case equivalence point and end point will coincide.

Explanation:

When the water freezes, the variable which changes is the temperature because as we reduce the temperature, the particles will come closer to each other and the average kinetic energy of the particles of water decreases. Hence, the water freezes below 0°C.

In the case of melting, the temperature is increased which means that the particles move away from each other and the average kinetic energy of the particles of water at this temperature increases. Hence, the water melts above 100°C.

Iridium (Ir) is a element which is metal. Therefore, the correct option is option C among all the given options.

Metal is any of a group of substances with strong thermal and electrical conductivity, malleability, ductility, as well as high light reflection. Typically, metals are crystalline solids. The free-electron hypothesis provides the best justification for the high thermal and electrical conductivity and high of the simple elements.

They typically have a very straightforward crystal structure that is characterized by dense atom packing and a high level of symmetry. Metal atoms often have fewer than half of their total number of electrons in the outermost shell. This property makes metals less likely to combine to create compounds. Iridium (Ir) is a element which is metal.

Therefore, the correct option is option C. Iridium (Ir) is a element which is metal.

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Answer: The mass of mercury will be 20.15 g.

Explanation:

Density is defined as the mass contained per unit volume.

[tex]Density=\frac{mass}{Volume}[/tex]

Given : Mass of bromine = ?

Density of bromine= [tex]3.1g/ml[/tex]

volume of bromine = 6.5 ml

Putting in the values we get:

[tex]3.1g/ml=\frac{mass}{6.5ml}[/tex]

[tex]mass=20.15g[/tex]

Thus the mass of bromine is 20.15 g.

Answer:

The molecular formula is Fe₂O₃

Explanation:

The molar mass of the compound is 199.55 g/mol; this means that if we have 1 mol of the compound, we'd have 199.55 g, we'd also have:

Now we calculate the moles of each element present in the given masses, using their atomic masses:

Then in 1 mol of the compound, there's 2.50 mol Fe and 3.75 mol O:

We convert the coefficients into integers (Divide them by the lowest number among them and multiply them by two):

Final answer:

A common product of acid-base neutralization reaction is water and a salt.

Explanation:

A common product of acid-base neutralization reaction is water and a salt. In this reaction, an acid and a base react to form a salt and water. For example, when hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH), the products are sodium chloride (NaCl) and water (H2O).

The mixing of enantiomers D and L yields a zero-degree observed rotation. Dilution of D with solvent maintains the same observed rotation, and also doesn't change the specific rotation.

Enantiomeric compounds D and L are mirror images of each other, thus they will rotate plane-polarized light equally but in opposite directions. Therefore, when these are mixed in equal volumes, the rotation of one enantiomer will cancel out the rotation of the other, resulting in an observed rotation of 0 degrees.

The solution's concentration is being halved when the solution of D is diluted with an equal volume of solvent. But, because the observed rotation is directly proportional to the path length and inversely proportional to the concentration, the observed rotation will remain the same at 0.20 degrees, because you're essentially doubling the path length while halving the concentration.

The specific rotation will stay the same i.e 0.20 degrees after the dilution in question c), because it is an intrinsic property of the substance D and does not change with concentration or path-length.

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Answer:false

Explanation:

Option C: The dissociation of a polar covalent compound in water.

Sugar is made up of sucrose molecules containing polar covalent bonds. They have same type of oxygen-hydrogen covalent bonds that are present in water.

Since, sugar is not an ionic compound, option a and option b are incorrect. Also, due to same type of bonding in water and sugar molecules there will be no such force of attraction between them, this will opt out the option d.

Thus, dissolution of sugar in water is the dissociation of a polar covalent compound in water and option c is correct.

Final answer:

The dissolution of sugar in water is due to the strong pull of water molecules on a polar covalent compound, like sugar, and is best explained by option d.

Explanation:

The dissolution of sugar in water is best described by option d, a strong pull of water molecules on a polar covalent compound. Sugar molecules are classified as polar covalent compounds because they contain regions of hydrogen-oxygen polar bonds. Due to the polarity of the water molecule, it can interact with these polar regions within sugar molecules through intermolecular forces. These interactions facilitate the separation of the sugar molecules into the solution, where they are surrounded by water molecules, leading to dissolution.

Water itself is a polar molecule, having a partial negative charge on the oxygen atom and a partial positive charge on the hydrogen atoms. Water molecules can surround the sugar molecules, aligning their charges with the opposite charges in the sugar molecule. This is what strongly pulls the sugar molecules apart and allows them to interact with more water molecules until they are evenly dispersed — thus the sugar is dissolved in the water due to the hydration process.

Answer:

A) CHCl3

Explanation:

Polarity arises due to the difference in the electronegativity between two atoms forming a chemical bond. This difference also creates a dipole. A molecule is said to be polar if it has a net dipole moment. In symmteric molecules the dipole moments tend to cancel out making them non-polar.

A) CHCl3 is a tetrahedral molecule in which the central C atom is bonded to 3 Cl and 1 H atom. This molecule is not symmteric since there are 3 C-Cl and  C-H bonds. Therefore, it will have a net dipole and will be polar

B) CCl4 is also a tetrahedral molecule, but symmetric in nature. Hence it will be non-polar

C) CO2 is a linear molecule where the dipole moments cancel out making it non-polar

C) CH4 is also a tetrahedral molecule and symmetric in nature. Hence it will be non-polar

A. CHCl₃ (chloroform) is the polar compound due to its tetrahedral structure with non-identical atoms and the resulting imbalance in electron distribution.

The compound likely to be a polar compound is CHCl₃. CHCl₃, or chloroform, is a polar molecule due to the uneven distribution of charge within its tetrahedral structure. Although the molecule has a tetrahedral geometry, the atoms bonded to the central carbon are not identical; there is one hydrogen and three chlorine atoms. Chlorine is more electronegative than carbon, and carbon is more electronegative than hydrogen, resulting in polar C-Cl bonds with a larger bond moment compared to the C-H bond. The difference in electronegativity and the arrangement of the atoms causes the bond dipole moments not to cancel out, yielding an overall dipole moment for the molecule. In contrast, molecules such as CCl₄ and CO₂ have symmetrical shapes and equal sharing of electrons, which result in nonpolar characteristics, while CH₄ also has a symmetrical tetrahedral structure with no significant differences in the electronegativity of the bonded atoms, rendering it nonpolar as well.

The atomic weight of hydrogen is approximately 1 atomic mass unit. It is the lightest element with an atomic number of 1 and it consists mainly of one proton and one electron. The atomic weight represents the weighted average atomic mass of hydrogen's isotopes.

The atomic weight of hydrogen is often considered to be 1. This value is based on a standard atomic weight scale where hydrogen, the lightest element with the atomic number, Z, of 1, sets the reference point for the scale. The atomic mass of hydrogen is approximately 1 atomic mass unit (u), which is a unit derived from the mass of a carbon-12 atom. Since a hydrogen atom consists of one proton and one electron, and has no neutrons, its atomic mass is very close to 1 u. The actual mass of a hydrogen atom is about 1.7 x 10⁻²⁷ kg. However, in chemical reactions and on the periodic table, a weighted average of the atomic masses of the different isotopes of hydrogen (such as protium with no neutrons, deuterium with one neutron, and tritium with two neutrons) is used, leading to a slightly different average atomic mass of approximately 1.008. It is critical in chemistry to distinguish between the atomic number, which is the number of protons in the nucleus of an atom, and the atomic mass or atomic weight, which is the weighted average mass of an atom's isotopes as they occur naturally.

Answer:

The correct answer is option B) It would sink directly to the bottom.

Explanation:

Hello!

Let's solve this!

Generally, solids have a higher density than liquids. In this case the densities are differentiated between the syrup, the oil and the water.

I think the solid would sink to the bottom.

After the explanation, we conclude that the correct answer is option B) It would sink directly to the bottom.

The best tool for Derek to use for delivering 25.00 mL of a sodium hydroxide solution is a volumetric pipette. Volumetric pipettes ensure precise volume measurements needed in laboratory settings.

To accurately measure and deliver 25.00 mL of a sodium hydroxide solution, the best tool for Derek to use is a volumetric pipette. Volumetric pipettes are specifically designed for precise volume measurements and are commonly used in laboratory settings to ensure accuracy.

Here’s a step-by-step guide on how Derek can use the volumetric pipette:

By using a volumetric pipette, Derek can be confident that he has delivered exactly 25.00 mL of the sodium hydroxide solution, which is critical for accurate chemical preparations and reactions.

The correct options are as follows:

17. C.

Radioactive decay refers to the process by which an unstable atomic nucleus loses energy by giving out radiations. The radiations emit can be in form of alpha or beta particles or gamma rays. Radioactive decay is a random process, that is, one can not predict when it would happen. Radioactive decay occurs when the nucleus of an atom decay and no longer have enough binding energy to hold the atomic sub particles together.

18. B.

Radioactive decay occurs when the nucleus no longer have enough energy to hold the sub particles in the nucleus together. This situation always occur when there are excess protons or neutrons in the nucleus of the atom. In the nucleus of an atom, two forces are usually at work, nuclear and electrostatic forces. While proton experience both of these forces, neutron only experience the nuclear force. These two forces that are in opposition bring about radioactive decay.

Radioactive decay occurs when the nucleus of an atom decays. The correct answer is

Radioactive decay occurs due to the electric force and nuclear forces being in opposition to each other.

Radioactive decay involves the spontaneous transformation of unstable atomic nuclei into more stable configurations, resulting in the emission of particles or electromagnetic radiation.

Reasons

In an atomic nucleus, protons are positively charged particles, and they experience repulsive electric forces due to their like charges. However, nuclear forces, specifically the strong nuclear force, help hold the protons and neutrons together in the nucleus. When the balance between these forces is disrupted, such as when the nucleus becomes unstable, radioactive decay can occur as the nucleus seeks a more stable configuration.

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Final answer:

The complete ionic equation for the neutralization of HCl by NaOH is Na+ + OH- + H+ + Cl- → H2O + Na+ + Cl-. The net ionic equation, omitting the spectator ions Na+ and Cl-, is H+ + OH- → H2O.

Explanation:

The total ionic equation for the neutralization reaction between sodium hydroxide (NaOH) and hydrochloric acid (HCl) is written as:

Na+ (aq) + OH− (aq) + H+ (aq) + Cl− (aq) → H₂O(l) + Na+ (aq) + Cl− (aq)

In this reaction, the Na+ and Cl− ions are spectator ions and do not participate in the actual neutralization. Thus, the net ionic equation, which shows the actual chemical change, is simply:

H+ (aq) + OH−(aq) → H₂O(l)

Here, the hydrogen ion (H+) from the acid reacts with the hydroxide ion (OH−) from the base to form water (H₂O), which is the only non-ionic product.