Science pls help me having trouble on the third one

Answer:

NO2 (nitrogen dioxide)

Explanation:

The empirical formula is the formula of the compound with its proportions of each element being in the simplest mole ratio.

That being said, first, we find the number of moles of each element.

n(N) = mass present/molar mass (m/M) = 42.05/14.01 (use a periodic table to locate the molar mass)

n(N) = 3.00143 mol

n(O) = m/M = 95.95/16.00 = 5.99688 mol

∴ the ratio of nitrogen to oxygen = 3.00143 : 5.99688

divide both sides by 3.00143, and we get 1 : 1.998,

which we can then round up to 1 : 2.

Hence, the empirical formula of the compound is \(NO_{2}\)

Filtration is a separation method used to separate out pure substances in mixtures comprised of particles some of which are large enough in size to be captured with a porous material. Particle size can vary considerably, given the type of mixture.

Evaporation is a technique used to separate out homogeneous mixtures that contain one or more dissolved salts. This process drives liquid components out of solid components. This process usually heats the mixture until the liquid is gone.

Distillation is an effective method of separating mixtures of two or more pure liquids. Distillation is a purification process that vaporizes, condenses, and separates the components of a liquid mixture.

Chromatography is the separation of a mixture by passing it in solution or suspension, or as a vapor through a medium in which the components move at different rates. Thin-layer chromatography is a special type of chromatography used for separating and identifying mixtures that are or can be colored especially pigments.

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Polymerization because monomers are joined to form a larger molecule. These units are linked together with different types of bonds depending on the class of the molecule such as carbohydrates, lipids, or proteins.

Answer:

C

Explanation:

Polymerization

Option A.

The number of molecules of carbon tetrachloride in 6.32 mg of the compound is 2.47 x 10¹⁹ molecules.

The molecular mass of Carbon tetrachloride is calculated as follows;

Molecular formula = CCl₄

CCl₄ = (12) + (35.5 x 4)

CCl₄ = 154 g/mol

The number of moles of carbon tetrachloride in 6.32 mg is calculated as follows;

n = reacting mass / molar mass

n = (6.32 x 10⁻³) / (154)

n = 4.1 x 10⁻⁵ moles

1 mole of CCl₄ = 6.02 x 10²³ molecules

4.1 x 10⁻⁵ moles of CCl₄ = ?

= 2.47 x 10¹⁹ molecules

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Answer:

Thunder!! Hope this helps!!

Answer:

D.to prevent dilution of the base, which may affect the results

Explanation:

edge

Answer:

The answer is D to prevent dilution of the base, which may affect the results

I just finished the test, good luck!

Explanation:

A double replacement reaction, also known as a double displacement reaction or a metathesis reaction, is a type of chemical reaction in which ions are exchanged between two compounds option(3).

In this reaction, the positive and negative ions of two compounds switch places, resulting in the formation of two new compounds.

The general form of a double replacement reaction is AB + CD → AD + CB, where A, B, C, and D represent elements or groups of elements. During the reaction, the cations of the compounds (positively charged ions) trade places, as do the anions (negatively charged ions). This exchange of ions leads to the formation of two new compounds, with the cation of one compound combining with the anion of the other compound.

Unlike single replacement reactions where a single element replaces another in a compound, double replacement reactions involve the exchange of ions. The reaction typically occurs in aqueous solutions or when compounds are dissolved in a solvent. However, double replacement reactions can also occur in other states, such as when two ionic compounds are in the solid state and react.

To summarize, a double replacement reaction involves the exchange of ions between two compounds, resulting in the formation of two new compounds. This reaction does not involve the loss of atoms or the exchange of electrons between individual atoms.

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Answer:

By their properties ;)

Explanation:

\(\Large \boxed{\sf by \ their \ properties}\)

Every element has a set of particular characteristics. Each has a unique atomic and mass number because they contain a different ratio of protons and neutrons. The number of protons in an element mirrors the element's atomic number. The mass number equals the sum of the element's protons and neutrons.

According to increasing atomic numbers, chemical elements get organized. Periods and groups are the names of the horizontal rows and vertical columns, respectively. The chemical characteristics of elements within the same group are comparable due to their similar valency and number of outer electrons.

Answer:

nitrogen and oxygen.   air we breathe is made up mostly of nitrogen molecules. Nitrogen atoms really like to stick to each other, which is why it’s hard to get nitrogen to react with

Explanation:

please tell me if I'm right ;)

The mass of water needed to absorb 456 J is 1.44 g

We'll begin by calculating the change in the temperature of the water.

Initial temperature of water (T₁) = 22.7 °C

Final temperature (T₂) = 98.3 °C

ΔT = T₂ – T₁

ΔT = 98.3 – 22.7

Heat absorbed (Q) = 456 J

Change in temperature (ΔT) = 75.6 °C

Specific heat capacity of water (C) = 4.184 J/gºC

Q = MCΔT

456 = M × 4.184 × 75.6

456 = M × 316.3104

Divide both side by 316.3104

M = 456 / 316.3104

Therefore, the mass of the water is 1.44 g

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With the production of Jacopo Peri's mostly forgotten Dafne in Florence in 1598, opera began in Italy at the end of the 16th century.

Particularly from Claudio Monteverdi's L'Orfeo and quickly spread throughout Europe: Jean-Baptiste Lully in France, Henry Purcell in England, and Heinrich Schütz in Germany

The first nation where opera gained popularity was Italy. Claudio Monteverdi and Jacopo Peri called it home. This exciting form of entertainment eventually spread throughout the remainder of Europe. Italy, France, and Germany are the primary producers of opera.

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Answer:410.6 g

Explanation:

The majority of the lead(II) iodide in the solution precipitates out as a yellow solid flag.

Define lead iodide?

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Answer:

Its Vog

Explanation:

Answer:

here are several resons that fossil foraminifera are especially valuable for determining the relative ages of marine rock layers. They have been around since the Cambrian, over 500 million years ago. They show fairly continuous evolutionary development, so different species are found at different times.

Answer:

b and then c

thanks for the brainly points

a. Sc3+: Scandium (Sc) has an atomic number of 21. When it forms Sc3+ ions, it loses three electrons.

The electron configuration of Sc3+ is [Ar] 3d0 4s0. Since all the electrons are paired, Sc3+ has zero unpaired electrons.

b. ??2: The question mark notation indicates an unknown element. Without knowing the specific element, we cannot predict the number of unpaired electrons. Each element has a unique electron configuration and number of unpaired electrons based on its atomic number and position in the periodic table.

c. Mn3+: Manganese (Mn) has an atomic number of 25. When it forms Mn3+ ions, it loses three electrons. The electron configuration of Mn3+ is [Ar] 3d4 4s0. In the 3d subshell, four of the five electrons are paired, while one electron remains unpaired. Therefore, Mn3+ has one unpaired electron.

d. Cr2+: Chromium (Cr) has an atomic number of 24. When it forms Cr2+ ions, it loses two electrons. The electron configuration of Cr2+ is [Ar] 3d4 4s0. In the 3d subshell, four of the five electrons are paired, leaving one unpaired electron. Therefore, Cr2+ has one unpaired electron.

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Answer:

Answer

Explanation:

Evidence from fossils, glaciers, and complementary coastlines helps reveal how the plates once fit together. Fossils tell us when and where plants and animals once existed. ... This distribution of fossils led to theories that the southern continents were once joined in a supercontinent called Gondwana.

Answer: Evidence from fossils, glaciers, and complementary coastlines helps reveal how the plates once fit together. Fossils tell us when and where plants and animals once existed.

Explanation: I hoped that helped plzz mark as brainliest !!

The number of protons in an atom of copper is 29.

It can be determined from the element symbol, Cu, which stands for Copper. The atomic number of an element is the number of protons in the nucleus of an atom of that element and is typically located above the element symbol. In this case, the atomic number of copper is 29, as indicated by the number 29 above the element symbol Cu. This is the information provided in the square.

Additionally, we can calculate the number of neutrons by the given information.

The number of neutrons= Mass number - Atomic number.

In this case,

The number of protons in Cu= 63 - 29 = 34.

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Answer:

6.02 x 10²³ electrons

Explanation:

Given parameters:

Mass of H₂  = 2g

Unknown:

Number of electrons = ?

Solution:

To find the number of electrons, we must determine the number of moles of H₂ first.

 Number of moles  = \(\frac{mass}{molar mass}\)  

  Molar mass of H₂   = 2(1)  = 2g/mol

Number of moles  = \(\frac{2}{2}\)   = 1mol  

1 mole of a substance contains 6.02 x 10²³ particles

the particles can be protons, neutrons, electrons

So,

  2g of H₂ will contain 6.02 x 10²³ electrons.

To calculate the pH of the resulting solution after titrating 2.0 ml of 0.10 M NH3 with 25 ml of 0.10 M HCl, a detailed calculation is needed.

Given the volumes and concentrations of NH3 and HCl, we can determine the number of moles for each compound. The balanced chemical equation for the reaction between NH3 and HCl is NH3 + HCl → NH4Cl. By using the formula C * V = n (where C is concentration, V is volume, and n is moles), we find that NH3 has 0.0002 moles and HCl has 0.0025 moles. Since the reaction is 1:1, all NH3 is consumed, resulting in 0.0002 moles of NH4Cl. Considering the concentration of NH4Cl and its hydrolysis, the pH of the resulting solution is 9.25.

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The p-value would depend on the calculated chi-square statistic and the degrees of freedom associated with the test.

To determine the p-value for the given scenario, we need to perform a statistical test, such as a chi-square test, to assess the association between gender and having a major co-existing condition (MCC).

The observed data can be summarized in a contingency table as follows:

Male 195 105

Female 205 245

To calculate the p-value, we would perform a chi-square test on this contingency table, comparing the observed frequencies to the expected frequencies under the assumption of independence between gender and MCC.

After conducting the chi-square test, the resulting p-value will indicate the probability of observing the given data or data more extreme if there is truly no association between gender and MCC.

However, without the expected frequencies or the results of the chi-square test, it is not possible to determine the exact p-value. Therefore, none of the provided options (A. 49, B. 53, C. 59, D. 50) can be considered as the correct answer. The p-value would depend on the calculated chi-square statistic and the degrees of freedom associated with the test.

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The fluid-filled interior compartment of the thylakoid network is referred to as the: Lumen

The thylakoid lumen is an aqueous phase that is continuously enclosed by the thylakoid membrane. It is essential for photophosphorylation during photosynthetic activity. Protons are hyped across the thylakoids into the lumen during the light-dependent reaction, making it acidic down to pH 4. The lumen in the chloroplast is referred to as the stroma. The stroma is the whitish fluid that surrounds the grana (thylakoids stacks) within the chloroplast. A lumen is the chloroplast membrane that surrounds space. Light energy is captured by photosystems found in thylakoid membranes. The thylakoid membrane contains enzymes required for photosynthesis's light-dependent reactions. Hydrogen ions are pumped into the thylakoid space, or lumen, during these reactions.The thylakoid space has an acidic pH due to the high concentration of hydrogen ions.

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Hello!

Answer:

The answer is d. H₂S.

Explanation:

The bond angle decreases as the electronegativity of the central atom decreases.

The electronegativity of the elements in the answer choices is in the order N > P > S > Se.

Therefore, H2S has the smallest bond angle.

Conclusion:

The smallest bond angle is H₂S.

The first element whose atomic number is 21 is Scandium and the second element whose atomic number is 7 is Nitrogen. Based on electronic configuration

Electronic configuration is a systematic way of distributing the electrons in their orbitals  Electron configurations of atoms follow a standard notation in which all electron-containing atomic subshells (with the number of electrons they hold written in superscript) are placed in a sequence.

Electron Configurations are useful for:

Determining the valency of an element.

Predicting the properties of a group of elements (elements with similar electron configurations tend to exhibit similar properties).

Interpreting atomic spectra.

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Answer:

Chlorine is more electronegative than iodine. The electronegativity of chlorine is 3.16. The electronegativity of iodine is 2.66.

Boiling stones prevent the solution from boiling too violently during reflux.

During reflux, a solution is continuously heated and cooled to promote the reaction. Boiling stones, also known as boiling chips or anti-bumping granules, are added to the solution to prevent the liquid from boiling too violently. This is because when a liquid reaches its boiling point, it can form bubbles of gas that rapidly rise to the surface and burst, causing the liquid to splatter and potentially spilling out of the reaction vessel.

Boiling stones provide nucleation sites for the bubbles to form, allowing for a gentler and more controlled boiling. They also increase the surface area of the liquid, which can improve heat transfer and promote a more efficient reflux. Common boiling stones include pieces of porcelain, glass, or silicon carbide, which are non-reactive and inert to most chemicals.

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Answer:Water is entirely composed of hydrogen and oxygen Being composed of such elusive and invisible elements

Explanation:this is helped to be clear by oxygen and invisible elements like nutrients