6) Select an element from the periodic table that interests you. Look it up on the internet and write down some
interesting facts about it. |

Answer:

104.5 and 109.5

Explanation:

Bond angle is the angle formed between three atoms which has at least two bonds present between them. The number of lone pairs in a covalent bond is a determinant of the bond angle as the lone pairs which are negatively charged repulses the bond pairs thereby creating a distortion and angle.

Studies have however shown that the bond angles in H3O are lesser than 109.5 and greater than 103.5. This provides a bond range of H3O.

Answer:

9.368g/mL

Explanation:

The density is defined as the mass of a compound in a determined volume.

Based on Archimedes' law, the volume of the piece of metal is the difference between the volume of the water + the inmersed piece - the original volume of water. That is:

Volume of the metal:

257.5mL - 229.0mL = 28.5mL

As the mass of the metal is 267.0g; its density is:

Density:

267.0g / 28.5mL =

Answer:

0.394g

Explanation:

At 78°C, you can dissolve, in 10mL of ethanol, 0.424g of the compound will dissolve. Then, you must filter the solution.

You take the filtrate of the solution in ethanol and cool it to 0°C. Om mL, only 0.03g of the compound will remain in solution. The other part is the purified compound.

Its mass (Theoretical yield) is:

0.424g - 0.030g =

Answer:

spontaneous

Explanation:

Electrons in a cathode ray tube are produced at the cathode and move towards the anode which is the the positive electrode.

This flow of electrons is spontaneous because electrons flow from a point of negative electric potential to a point of positive electric potential, hence the answer above.

Answer:

Its a shift of about 200ppm

Explanation:

because we know that a chemical shift explains the resonating frequency of a particular nucleus in relation to its standard as in a magnetic field so that

carbonyl group in aldehydes and ketones is 200ppm

Answer:

See figure 1

Explanation:

If we want to find the acid and the Brønsted-Lowry base, we must remember the definition for each of these molecules:

-) Acid: hydrogen donor

-) Base: hydrogen acceptor

In the caffeine structure, we have several atoms of nitrogen. These nitrogen atoms have the ability to accept hydronium ions ([tex]H^+[/tex]). Therefore the caffeine molecule will be the base since it can accept

If caffeine is the base, the water must be the acid. So, the water in this reaction donated a hydronium ion.

Thus, caffeine is the base and water the acid. (See figure 1)

In the reaction of caffeine with water, H₂O and C₈H₁₁N₄O₂⁺ are Brønsted-Lowry acids while C₈H₁₀N₄O₂ and OH⁻ are Brønsted-Lowry bases.

Caffeine reacts with water in an acid-base reaction. We want to identify acids and bases according to Brønsted-Lowry theory.

It is a theory that classifies substances as acids and bases according to their behavior in a reaction.

The chemical equation for the acid-base reaction between caffeine and water is:

C₈H₁₀N₄O₂ + H₂O ⇄ C₈H₁₁N₄O₂⁺ + OH⁻

C₈H₁₀N₄O₂ accepts a H⁺ so it is a base while H₂O donates a H⁺ so it is an acid. This reaction is reversible, so we can also state that C₈H₁₁N₄O₂⁺ is an acid because it donates a H⁺ and OH⁻ is a base because it accepts a H⁺.

In the reaction of caffeine with water, H₂O and C₈H₁₁N₄O₂⁺ are Brønsted-Lowry acids while C₈H₁₀N₄O₂ and OH⁻ are Brønsted-Lowry bases.

Learn more about Brønsted-Lowry acid base theory here: https://brainly.com/question/7256753

Answer:

2.48x10¹³ miles is the distance from the earth to Proxima Centauri

Explanation:

Light years is an unit of distance used in Astronomy. That is because 1 light year = 9.461x10¹²km; a real big distance used in the science that study the universe.

In km, 4.22 light years are:

4.22 light years * (9.461x10¹²km / 1 light year) = 3.9925x10¹³km

As 1 mile = 1.60934km, this distance in miles is:

3.9925x10¹³km * (1 mile / 1.60934km) =

Answer: (a) BE = 1.112 MeV

               (b) BE = 7.074 MeV

               (c) BE = 7.767 MeV

               (d) BE = 8.112 MeV

Explanation: Binding energy per nucleon is the average energy necessary to remove a proton or a neutron from the nucleus of an atom. It is mathematically defined as:

[tex]BE = \frac{\Delta m.c^{2}}{A}[/tex]

Where

Δm is a difference in mass known as mass defect

A is atomic mass of an atom.

Mass Defect is determined by:

[tex]\Delta m =Zm_{p}+(A-Z)m_{n} - m_{nuc}[/tex]

where:

Z is atomic number

[tex]m_{p}[/tex] is mass of proton

[tex]m_{n}[/tex] is mass of neutron

[tex]m_{nuc}[/tex] is mass of the nucleus

Mass of proton is 1.007825u.

Mass of neutron is 1.008665u.

The unit u is equal to 931.5MeV/c².

(a) 2H(deuterion): Given: Z = 1; A = 2; [tex]m_{nuc}[/tex] = 2.014102u

[tex]\Delta m =1(1.007825)+1(1.008665) -2.014102[/tex]

[tex]\Delta m =0.002388u[/tex]

[tex]BE = \frac{0.002388.c^{2}}{2}.931.5\frac{MeV}{c^{2}}[/tex]

BE = 1.112MeV

(b) 4He (Helium): Given: Z = 2; A = 4; [tex]m_{nuc}[/tex] = 4.002603

[tex]\Delta m =2(1.007825)+2(1.008665) -4.002603[/tex]

[tex]\Delta m =0.030377u[/tex]

[tex]BE = \frac{0.030377.c^{2}}{4}.931.5\frac{MeV}{c^{2}}[/tex]

BE = 7.074MeV

(c) 18O (Oxygen): Given: Z = 8; A = 18; [tex]m_{nuc}[/tex] = 17.999160

[tex]\Delta m =8(1.007825)+10(1.008665) -17.999160[/tex]

[tex]\Delta m =0.15009u[/tex]

[tex]BE = \frac{0.15009.c^{2}}{18}.931.5\frac{MeV}{c^{2}}[/tex]

BE = 7.767MeV

(d) 23Na (Sodium): Given: Z = 11; A = 23; [tex]m_{nuc}[/tex] = 22.989767

[tex]\Delta m =11(1.007825)+12(1.008665) -22.989767[/tex]

[tex]\Delta m =0.200288u[/tex]

[tex]BE = \frac{0.200288.c^{2}}{23}.931.5\frac{MeV}{c^{2}}[/tex]

BE = 8.112MeV

Answer:

= -13.6 eV

Explanation:

E = -13.6 ÷ [tex]\frac{Z^{2} }{n^{2} }[/tex]

where n is the principal state

Z is atomic number

and E is energy in electron volts.

Given that n = 2 and Helium Z = 2

⇒ E = -13.6 ÷ [tex]\frac{2^{2} }{2^{2} }[/tex]

= -13.6 eV

I believe this is helpful and easy to follow.

Answer: The answer can be found on CHEG

Explanation:

Answer:

By definition:

Example:

If I study hard in school, I will get good grades.

Answer:

D) Measure 58.44g NaCl, dissolve it into 400ml water, and then top off to 500ml in a volumetric flask.

Explanation:

2.00M NaCl is a solution that contains 2.00 moles of NaCl per liter of solution.

As you want to prepare 500mL = 0.500L of the solution you need:

0.500L * (2.00 moles / L) = 1.00 moles of NaCl are required to prepare the solution.

Now, to convert these moles to grams you must use Molar weight (58.44g/mol) as follows:

1 moles of NaCl * (58.44g / mol) = 58.44g of NaCl are required to dissolve in 500mL to prepare the 2.00M solution.

And right option is:

-You can't top off a solution before dissolve all solute because it is possible the volume changes-

Answer:

D) Measure 58.44g NaCl, dissolve it into 400ml water, and then top off to 500ml in a volumetric flask.

Explanation:

I got it right in class!

Hope this Helps!! :))

Answer:

The correct answer is "transferred; unequally shared; equally shared".

Explanation:

Ionic bonding occurs when a positively charged atom (cation) interacts with a negatively charged atom (anion). In ionic bonding, the cation transfers its electron to the anion. In polar covalent bonding, electrons are unequally shared. This means that the electrons spend more time in an atom than the other, which gives partial positive and negative charges to the atoms. On the other hand in nonpolar covalent bonding, the electrons are equally shared and no charges are created.

Answer:

The United States took first steps to keep the air clean.

Explanation:

The US environmental protection agency was created in the year 1970 so this option is wrong.

November 15, 1990 however was a milestone in keeping the air clean, the signing f the amendments, the amendments set the stage for protecting the ozone layer, improving air quality and visibility.

The correct option is option A; The United States took first steps to keep the air clean.

Answer:

C. Modifications and improvements were made to the Clean Air Act.

Explanation:

The Clean Air act was originally established in 1970 and was concerned with the aim of protecting people and the environment in general from polluted air. Polluted air could cause different illnesses and environmental degradation.

The law was amended in 1990 in which modifications and improvements were made to the Clean Air Act. There was the need to reduce acid rain, toxic emissions which could deplete the ozone layer and cause varying respiratory illnesses in humans and to increase visibility.

Answer:

millileter????

This question is incomplete, the complete question is;

An electrochemistry lab was conducted. What voltage would have been observed if you had switched the position of the electrodes but not the solutions for any of the electrochemical cells? (e.g. placed Cu electrode with Zn²+ and Zn with Cu²+).

Clearly explain your answer, include what would have happened in each cell

Answer:

E°cell = +1.10V

Explanation:

At lower reduction potential, electrode acts as an anode ( -ve )

At higher reduction potential, electrode acts as a cathode ( +ve )

NOW

standard reduction of Cu⁺² / Cu electrode,

E° cu⁺²/cu = 0.34V

standard reduction potential of zn⁺² / zn electrode,

E° zn⁺/zn = -0.76V

Zn has lower reduction potential, therefore it acts as an anode and standard reduction potential of Cu has higher reduction potential so it acts as a cathode.

now we know that

E°cell = E°cathode - E°anode

we substitute

E°cell = 0.34V - ( -0.76V)

E°cell = +1.10V

Therefore there is no flow of e- in the wire when the copper electrode placed in Zn²⁺ ( electrode reverse). When zinc electrode placed in copper solution, copper deposition in zinc electrode takes place, so zinc is converted into Zn ion and no flow of e- will occur in outer circuit.

∴ The voltage becomes zero

Answer:

b) maintains the pH of blood near 7.4.

c) regulates the blood pH at 7.4 +/- one pH unit.

f) is facilitated by the enzyme carbonic anhydrase, which interconverts carbon dioxide and water to carbonic acid (ionizes into bicarbonate and H^+).

Explanation:

The pH of human blood is slightly acidic i. e. 7.4. The enzyme carbonic anhydrase is responsible for the regulation to neutral and prevent it from acidic. the enzyme carbonic anhydrase helps in the conversion of carbon dioxide to carbonic acid and bicarbonate ions. When the blood reach to lungs, the bicarbonate ions convert back to CO2 and this carbondioxide is exhaled from the body.

Explanation:

What type of bond forms in iron (II) chloride?

Answer:

( CH_3) _2CHCH_2CH_2CO_2CH_2CH

Answer:

D

Explanation:

Chemical shift is given as

Frequency/frequency of instrument

Let c = chemical shift

F = frequency

I = frequency of instrument

Chemical shift = frequency/frequency Instrument

1.25ppm = Frequency /400

We cross multiply to find frequency

Frequency = 400 x 1.25

Frequency = 500Hz

Option d is the answer since it is 500hz

washing dishes only when the dishwasher is full

Answer:

16.5

Explanation:

Answer:

is your answer is 16.5 km

Answer:

48 molecules of CO₂

Explanation:

I think you made a mistake in your question.  The formula for propane is C₃H₈, not C₃H₃.  But, I will give you the answer for both cases.

For C₃H₃:

First you have to balance the equation.

4 C₃H₃  +  15 O₂  ⇒  12 CO₂  +  6 H₂O

Next, you need to use the mole ratios between C₃H₃ and CO₂ to find the amount of molecules of CO₂ you will produce with the given amount of C₃H₃.

(16 mol's C₃H₃) × (12 mol's CO₂/4 mol's C₃H₃) = 48 mol's CO₂

You will get 48 molecules of CO₂.

For C₃H₈:

Balance the equation.

C₃H₈  +  5 O₂  ⇒  3 CO₂  +  4 H₂O

Use the mole ratios between C₃H₈ and CO₂.

(16 mol's C₃H₈) × (3 mol's CO₂/1 mol's C₃H₈) = 48 mol's CO₂

You will get 48 molecules of CO₂ for this equation as well.

Answer:

An atom's smaller negative particles are at a distance from the central positive particles, so the negative particles are easier to remove.

Explanation:

Answer:

Solubility = [SO₄²⁻]

Explanation:

Solubility of Ag₂SO₄ can be determined by its ksp equilibrium:

Ag₂SO₄(s) ⇄ SO₄²⁻ + 2Ag⁺

Where 1 mole of silver sulfate dissolves producing 1 mole of sulfate ion and 2 moles of silver ion.

Solubility is defined as the amount of solid that can be dissolved per liter of solution.

The moles of Ag₂SO₄ dissolved are equal to moles of SO₄²⁻.

That means:

Given :

Initial volume , [tex]v_1=50\ ml[/tex] .

Final volume , [tex]v_2=300 \ ml[/tex] .

Initial molarity , [tex]M_1=0.45 \ M[/tex] .

To Find :

Molarity of  300 ml solution .

Solution :

We know , for constant moles .

[tex]M_1v_1=M_2v_2\\\\M_2=\dfrac{M_1v_1}{v_2}\\\\M_2=\dfrac{50\times 0.45}{300}\ M\\\\M_2=0.075\ M[/tex]

Therefore , the molarity of the resulting solution is 0.075 M.

Hence , this is the required solution .

Answer: A:Physical, B:Both, C: Chemical

Explanation:

Tearing paper is physical because only the appearance has changed. Melting wax can be either physical or chemical depending on whether the wax actually burns or not, burning a log is chemical because new substances are formed when wood burns.

Answer:

The products have a higher heat content than the reactants

Explanation:

Recall that the change in enthalpy for a reaction is obtained from

∆Hreaction= enthalpy of products - enthalpy of reactants

For an exothermic reaction, enthalpy of reactants > enthalpy of products, hence ∆Hreaction is negative.

This implies that the heat content of reactants is greater than that of products for an exothermic reaction. Hence the option selected in the answer is false as written.