help me with this please!!

1. ionic NaCl

2. covalent CO2

3.metallic ZnCu

Answer: D.  Scientific theories and laws develop from the acquisition of scientific knowledge.

Explanation:

The scientific knowledge is acquired by using the detail knowledge of scientific methodology which is used in both scientific theories and laws. The scientific methodology includes the observing things, making hypothesis on the basis of observation, testing the hypothesis, performing the experiment and concluding the results. The results obtain will contribute to new innovation and research which will further contribute to the scientific knowledge.

3

is the answer i do believe

 Over 344.76 K  the  forward reaction will be spontaneous

 calculation

ΔG  = ΔH° -TΔs

if ΔG =0

therefore  0 =ΔH°-TΔs

ΔH°   = TΔs

divide  both side  by   Δs

T = ΔH°/Δs

convert 34.2 kj into j

 that  is 1 kj = 1000 j

        34.2 kj =? j

by cross  multiplication

=[34.2 kj x 1000j / 1 kj] = 34200 j

T  is therefore = 34200 j÷99.2 j/k =344.76 k

if  T is greater than  344.76 k  the forward reaction  will be spontaneous

The calculation of temperature is done as follows:

T = ΔH°/ΔS°

= 34.2 kJ/mol / 99.2 × 10⁻³ kJ/molK

= 345 K

Since, ΔS° and ΔH° comes out to be positive for the given reaction. Hence, the given reaction is spontaneous at higher temperature and non spontaneous at lower temperature. Thus, it can be said that above 345 K, the given reaction will become spontaneous.

Muscles protect the network of nerves that run throughout the body

Answer:

Muscles protect the network of nerves that run throughout the body

Explanation:

I thank to

We should definitely seek shade to sun exposure between 10 A.M. and 4 P.M.

Hope this helped!

a) P^2=a^3=30.6^3=28650

b) P=28650=169 years

Final answer:

Neptune takes approximately 165 Earth years to complete one orbit around the sun, as it orbits at a distance of 30 AU from the sun.

Explanation:

The orbital period of Neptune, which is the time it takes for Neptune to complete one orbit around the sun, is approximately 165 Earth years. This is because Neptune orbits at an average distance of 30 astronomical units (AU) from the sun. One AU is the average distance between the Earth and the Sun, which is about 1.496×108 km. Given that Neptune is 4.490×109 km away from the Sun, and considering the substantial distance as compared to Earth's orbit, Neptune's year is much longer.

Answer: 18.42 grams of lead (II) sulfide will be produced in the given reaction:

Explanation: The reaction of lead (II) acetate and hydrogen sulfide follows:

[tex](CH_3COO)_2Pb+H_2S\rightarrow PbS+2CH_3COOH[/tex]

To calculate the moles, we use the formula:

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

Molar mass of lead (II) acetate = 325.29 g/mol

Given mass of lead (II) acetate = 25 g

Putting values in above equation, we get:

[tex]Moles=\frac{25g}{325.29g/mol}=0.0768moles[/tex]

We are given that hydrogen sulfide is present in excess, so limiting reagent is lead (II) acetate because it limits the formation of product.

By stoichiometry of the reaction,

1 moles of lead (II) acetate produces 1 mole of lead (II) sulfide

So, 0.0768 moles of lead (II) acetate will produce = [tex]\frac{1}{1}\times 0.0768[/tex] = 0.0768 moles of lead (II) sulfide.

Now, to calculate the mass of lead (II) sulfide, we use equation 1, we get:

Molar mass of lead (II) sulfide = 239.3 g/mol

[tex]0.0768mol=\frac{\text{Given mass}}{239.3g/mol}[/tex]

[tex]\text{Mass of lead (II) sulfide}=18.42g[/tex]

When 25.0 g of lead (II) acetate reacts with excess hydrogen sulfide, 18.37 grams of lead (II) sulfide are produced, based on stoichiometry and molar mass calculations.

To calculate the number of grams of lead (II) sulfide produced when 25.0 g of lead (II) acetate reacts with excess hydrogen sulfide, first, you need to write the balanced chemical equation for the reaction:

Pb(C₂H₃O₂)₂+ H2S ightarrow PbS + 2C₂H₄O₂

This indicates that one mole of lead (II) acetate produces one mole of lead (II) sulfide. Next, find the molar mass of lead (II) acetate and lead (II) sulfide:

Molar mass of Pb(C₂H₃O₂)₂ = 325.29 g/mol

Molar mass of PbS = 239.26 g/mol

Then, calculate the number of moles of lead (II) acetate:

25.0 g Pb(C₂H₃O₂)₂ times (1 mol / 325.29 g) = 0.0768 mol

Assuming complete reaction and that lead (II) acetate is the limiting reagent, the same number of moles of PbS will be formed. Finally, calculate the mass of PbS:

0.0768 mol PbS times (239.26 g/mol) = 18.37 g of PbS

Therefore, 18.37 grams of lead (II) sulfide are produced.

An atom's atomic number equals the number of protons and in a neutral atom, also, the number of electrons. The mass number equals the total number of protons and neutrons. Subtracting the atomic number from the mass number gives the number of neutrons.

In order to determine the number of protons, neutrons, and electrons an atom has, you need to understand the key terms: atomic number and mass number. The atomic number of an element represents the number of protons in an atom and, in a neutral atom, this also equals the number of electrons. The mass number (or atomic mass) is the total amount of protons and neutrons in an atom. To find out the number of neutrons in an atom, you subtract the atomic number from the mass number. Hence, if the atomic number (Z) represents the number of protons and the mass number (A) represents the number of protons plus neutrons, the formula A - Z = number of neutrons can be used to find the number of neutrons in an atom.

https://brainly.com/question/33054877

#SPJ12

The alkali metals takes column 1 A of the periodic table.some of them are hydrogen, potassium,lithium etc. The elements gets into their ionic +1 form because they easily lose their one electron in the outermost shell.This one electron is the outermost layer of electrons is responsible for the various properties of alkali metals.

Alkali metals all form cations with a +1 charge upon ionization due to the easy loss of their single valence electron. This is due to their large atomic radii and low first ionization energies.

The elements in the first column of the periodic table, known as alkali metals, include lithium, sodium, potassium, rubidium, cesium, and francium. These elements are characterized by having the largest atomic radii in their respective periods and the lowest first ionization energies, which makes it easy for them to lose their single valence electron. When ionized, alkali metals all form stable cations with a +1 charge.

The periodic table can thus be used as a tool to predict the charge of ions based on an element's location. For instance, all alkali metal ions have a +1 charge, and the convention is to write the number and then the sign, like Li+ or Na+, illustrating that each alkali metal cation has one positive charge.

Weathering is the process of breaking large rocks and boulders into much smaller ones. Weathering can be brought about by wind and water mostly. Sometimes even biological forces account for some types of weathering.

S+O2 =SO2 SULFUR DENOTE S  

TWO ATOM OF OXYGEN DENOTE O2

The unstable atomic nucleus of Uranium-238 emits ionizing particles and loses energy in order to achieve a stable state. This process is called the Radioactive decay. This isotope undergoes Alpha decay by emitting Alpha rays. It has a decay energy of 4.267 MeV.

Final answer:

The decay of uranium-238 to thorium-234 is represented by a nuclear equation that must balance in terms of both mass numbers and atomic numbers, owing to conservation laws. The emission of an alpha particle during the decay of U-238 results in Th-234, with the mass number decreasing by 4 and the atomic number by 2.

Explanation:

When uranium-238 decays to form thorium-234, this is represented by a nuclear equation owing to the transformation occurring within an atomic nucleus. According to conservation of mass and atomic numbers, the nuclear equation must balance, both in terms of the mass numbers and the atomic numbers. Considering uranium has an atomic number of 92 (Z = 92) and a mass number of 238, when it loses 2 protons and 2 neutrons which occurs during the emission of an alpha particle (He), we are left with thorium-234 (Th).

The balanced nuclear equation for this decay process is:

^238_92U → ^4_2He + ^234_90Th

This shows the loss of an alpha particle from uranium-238 which results in thorium-234. The sum of the mass numbers and atomic numbers on the reactant side must equal the sum on the product side, hence confirming that the equation is correctly balanced. The loss of four nuclear particles (2 protons and 2 neutrons) is accounted for by the alpha particle, reducing the mass number by 4 from 238 to 234, and dropping the atomic number from 92 to 90 which identifies the new element as thorium. Furthermore, this decay sequence continues as thorium-234 decays via beta emission to form protactinium-234, which then decays to uranium-234.

Aluminium has 3 valance electrons in its outer shell. This means that it would need to give up 3 electrons to achieve a full octet.

The answer is A or D  

the correct answer is c.

the answer is ( . a rocket in space )

Answer:

The correct option is B

Explanation:

The mass of an object is the amount of substances/molecules present in that object. The mass of an object remains the same anywhere regardless of gravity. In space, where there is no gravity, the mass of a rocket remains the same but the weight will be different because of zero gravity which means there will be no force of gravity pulling the rocket towards itself.

Hence, weight can be calculated as

Mass of an object (in kg) × gravitional field strength (in N/kg)

From the above formula, it can be deduced that weight is dependent on mass and gravity but mass is not (when you make mass the subject of the formula).

The uranium within these items is radioactive and should be treated with care. Uranium's most stable isotope, uranium-238, has a half-life of about 4,468,000,000 years. It decays into thorium-234 through alpha decay or decays through spontaneous fission.

1 and 2 are a metal - nonmetal pair - that kinda means ionic bond. Na and F are going to lose electrons.

3 [Nonmetals bond to each other covalently! Ne and O are nonmetals. O would need 2e to become stable. Either getting 2e (ionic bond) or sharing 2e (with H, for example). However, Ne is a noble gas, which means it is already doing fine with its 8e on its valence shell and isn't gonna share 2e of its electrons with O. So, despite the fact that they are both nonmetals, they won't form a covalent bond.

Sum up: they are 2 gases haha, and one of them is a noble one. They will never bond to each other covalently

4 - C and S - right answer

As they are both nonmetals (nonmetals bond to each other covalently, none of them is a noble gas, and so on)

Answer: The correct answer is Option b.

Explanation:

Single displacement reaction is defined as the reaction in which more reactive element displaces a less reactive element from its chemical reaction.

The reactivity of metal is determined by a series known as reactivity series. The metals lying above in the series are more reactive than the metals which lie below in the series.

When calcium metal reacts with hydrochloric acid, it leads to the formation of a salt known as calcium chloride and also releases hydrogen gas.

The chemical equation for the above reaction follows:

[tex]Ca(s)+2HCl(aq.)\rightarrow CaCl_2(s)+H_2(g)[/tex]

Hence, the correct answer is Option b.

Like the diagram we can see the the products of reaction are obtained with a amount of heat under the heat of reactants... so the reaction is exothermic and the Ea = E* - Eproducts = 100 - 40 = 60 kJ

There are different formula you need to keep in mind when solving for [OH-]

Given that pH = 6.10

pH + pOH = 14

6.10 + pOH = 14

pOH = 7.9

[OH-] = 10^(-pOH)

[OH-] = 10^(-7.9)

[OH-] = 0.000000013

[OH-] = 1.3 x 10^-8

The hydroxide ion concentration in an aqueous solution is equal to 10⁻⁸M.

pOH can be determined by taking the negative logarithm of the hydroxide ions concentration in the given aqueous solution.

Mathematically, pOH can be expressed in the form of hydroxide ion concentration as follows:

pOH = - log  [ OH⁻]                                                

and, [tex]pH + pOH = 14[/tex]                                                        ..............(1)

where [OH⁻] is the hydroxide ions concentration present in an aqueous solution.

Given, the value of pH of the solution containing hydroxide ions:

pH = 6.10

Substitute the value of the pH in equation (1):

pH - log [OH⁻] = 14

6.10 - log [OH⁻] = 14

log [OH⁻] = - 7.9

[OH⁻] = [tex]10 ^{-7.9}[/tex]

[OH⁻] ≈ 10⁻⁸ M

Therefore, the concentration of the hydroxide ions in an aqueous solution is equal to 10⁻⁸ M.

Learn more about pOH, here:

brainly.com/question/17144456

#SPJ5

Answer: pOH = 3.13

Ba(OH)2 is a very basic substance. The general formula for pOH is - log(OH)

Barium Hydroxide produces 2 moles of OH for every mole of Ba(OH)2 present in the solution.

0.00037 M = 3.7 * 10^-4 Ba(OH)2 will produce 2 *0.00037 M of OH-

OH- = 2* 0.00037 = 0.00074

pOH = - log(0.00074) = 3.13

Answer:

3.13

Explanation:

The isotope which is used as fuel in nuclear power generators is uranium - 235. THe nuclear symbol is  [tex]\rm_{92}^{235}U[/tex].

Isotopes are atoms of same element with different mass number. They may  differ in the physical and chemical properties also. Not all isotopes of an atom are stable. Some of them are radioactive and are unstable.

Uranium is 92nd element in periodic table. It is a radioactive element placed in among the actinides in f- block elements. Uranium undergo alpha or beta decay producing more stable nuclei with different composition.

Nuclear decay evolves energy and thus radioactive elements such as U are used as fuel in power generation plants.

An isotope is represented by the chemical symbol with the atomic number as subscript and mass number as superscript.The isotopic symbol of U is [tex]\rm_{92}^{235}U[/tex]. The mass number is 235. and the number of protons and neutrons are  92 and 143 respectively.

To find more on uranium, refer here:

https://brainly.com/question/9099776

#SPJ2

None Of the Above

Is the answer

Hope this helped plz mark

Hi There!

Question - What is a stationary front?

Answer - None of the above.

Why - The reason I say this because in a stationary front its made of low pressure systems so its not A or B. The wind blows the low pressure system which cause precipitation. If its not D then is C.

Hope This Helps :)

Gamma Decay in the nucleus is similar to Photon Decay in atoms. When a electron charges energy levels in the atoms, it  desposes of photon (with energy of order electron volts).

Answer:

1. It contains only one element.

Step-by-step explanation:

The formula of fullerene is C₆₀.

Fullerene is a compound. One molecule of fullerene contains 60 atoms of one element, carbon.

2. is wrong, because fullerene consists of only one element.

3. and 4. are wrong, because fullerene is a compound.

The answer would be 8 m/s. To find the answer you divide distance by time which is 16 divided by 2.