Question 18 of 32
What is a covalent bond?
OA. A bond in which molecules share electrons
OB. A bond in which atoms share electrons
C. A bond between ions of the same charge

Synthetic materials are made from natural resources and can be used for many purposes.

Synthetic materials are made by chemically changing the starting substances to create a material with different characteristics. Some examples of synthetic materials are plastics, medicines, and new fuels.

A synthetic substance may be chemically identical to a naturally-occurring substance or may be different.

Item is made from a synthetic material :

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Answer:

1. Thermometer– It is used to measure air temperature.

2. From time to time– In 2–4hrs after sunrise, the air temperature rises the fastest. Around 1hr before sun set, the air temperature drops the fastest. The solar radiation reaches its highest value at noon.

3. Anemometer– it is used to measure wind speed and direction.

4. Direction– The wind vane originally measures the direction of the wind, but, some modern ones have wind cups attached to them, to measure the wind speed.

5. Anemometer– It is a device that measures wind speed and direction. These, days, some modern wind vanes also measure wind speed.

Explanation:

I hope this helps.

Answer:

To separate a metal from its ore using acid and preserving desirable products such as gold.

Explanation:

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When One mole of hydrogen is burned in oxygen to produce water in the gas phase, 285.8 kJ of heat is released.Hence, option (D) is correct

An enthalpy change is approximately equal to the difference between the energy used to break bonds in a chemical reaction and the energy gained by the formation of new chemical bonds in the reaction.

It describes the energy change of a system at constant pressure. Enthalpy change is denoted by ΔH.

The energy change that occurs when one mole of a compound is burnt in excess oxygen under standard bis called the standard enthalpy change of combustion.

Hence, When One mole of hydrogen is burned in oxygen to produce water in the gas phase, 285.8 kJ of heat is released.Thus, option (D) is correct

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There are three sigma bonds, so hybridization of the molecule will be sp²

Answer:

photoelectric effect, phenomenon in which electrically charged particles are released from or within a material when it absorbs electromagnetic radiation. The effect is often defined as the ejection of electrons from a metal plate when light falls on it.

The concentration of the solution is 0.17M

The missing question is

What is the concentration of the solution ?

Molarity is the moles of solute in 1 liter of solution.

It is the measure of concentration of a solution in mol/l .

It is given that

5 grams of sodium chloride is dissolved to make 0.5 L of solution

the concentration of the solution

Molecular weight of Sodium Chloride = 58.44 g

58.44 g of NaCl = 1 mol

5g of NaCl = 5/58.44 = 0.086 moles

Molarity = 0.086 / 0.5

Molarity = 0.17 M

The concentration of the solution is 0.17M

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Taking into account the reaction stoichiometry, 4.515 grams of N₂ can be produced from 8.73 grams of H₂O₂ and 5.16 grams of N₂H₄.

In first place, the balanced reaction is:

N₂H₄ + 2 H₂O₂ → N₂ + 4 H₂O

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

The molar mass of the compounds is:

Then, by reaction stoichiometry, the following mass quantities of each compound participate in the reaction:

The limiting reagent is one that is consumed first in its entirety, determining the amount of product in the reaction. When the limiting reagent is finished, the chemical reaction will stop.

To determine the limiting reagent, it is possible to use a simple rule of three as follows: if by stoichiometry 34 grams of H₂O₂ reacts with 32 grams of N₂H₄, 8.73 grams of H₂O₂ reacts with how much mass of N₂H₄?

[tex]mass of N_{2} H_{4} =\frac{8.73 grams of H_{2} O_{2}x 32 grams of N_{2} H_{4} }{34grams of H_{2} O_{2}}[/tex]

mass of N₂H₄= 8.22 grams

But 8.22 grams of N₂H₄ are not available, 5.16 grams are available. Since you have less mass than you need to react with 8.73 grams of H₂O₂, N₂H₄ will be the limiting reagent.

Considering the limiting reagent, the following rule of three can be applied: if by reaction stoichiometry 32 grams of N₂H₄ form 28 grams of N₂, 5.16 grams of N₂H₄ form how much mass of N₂?

[tex]mass of N_{2} =\frac{5.16 grams of N_{2} H_{4} x28 grams of N_{2}}{32 grams of N_{2} H_{4} }[/tex]

mass of N₂= 4.515 grams

Then, 4.515 grams of N₂ can be produced from 8.73 grams of H₂O₂ and 5.16 grams of N₂H₄.

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The empirical formula for a compound composed of 0.0683 mol of carbon ( C ), 0.0341 mol of hydrogen ( H ), and 0.1024 mol of nitrogen ( N ) is  [tex]C_2HN_3[/tex].

An empirical formula tells us the relative ratios of different atoms in a compound.

Given data:

Moles of carbon = 0.0683 mol

Moles of hydrogen = 0.0341 mol

Moles of nitrogen = 0.1024 mol

Dividing each mole using the smallest number that is divided by 0.0341 moles.

We get:

Carbon= 2

Hydrogen=1

Nitrogen=3

The empirical formula for a compound is[tex]C_2HN_3[/tex].

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2 moles of ZnO are produced if 1 mole of Zn and 2 moles of [tex]O_2[/tex] is required.

A mole is defined as 6.02214076 × [tex]10^{23}[/tex] of some chemical unit, be it atoms, molecules, ions, or others. The mole is a convenient unit to use because of the great number of atoms, molecules, or others in any substance.

Balanced equation:

[tex]2 Zn + O_2[/tex] → [tex]2 ZnO[/tex]

For 2 moles of Zinc, we need 1 mol of Oxygen to produce 2 moles of Zinc oxide

For 1 mole Zn, we need 2 mol [tex]O_2[/tex] to produce 2 moles ZnO only.

Hence, 2 moles ZnO is produced.

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Answer:

C

Explanation:

Marble is the correct answer

Answer:

55.5g of calcium chloride is produced in the reaction.

Explanation:

To calculate the amount of calcium chloride.

The reaction of calcium carbonate with hydrochloride acid gives calcium chloride

CaCO₃ +  2HCl  →  CaCl₂  + CO₂  +  H₂O

Mass of calcium carbonate (CaCO₃)= 50.0g

Molecular mass of CaCO₃ = Ca + C + O₃

                                             = 40+ 12 + 3(16) = 100g

No of moles of calcium carbonate CaCO₃ = given mass / molecular mass

                                                                          = 50g/ 100

                                                                            = 0.5 moles

Molecular mass of calcium chloride = 40+ 2(35.5)=(40+71.0)= 111g/mol

1 mole of calcium carbonate gives = 1 mole of calcium chloride

0.5 moles of calcium carbonate gives= 0.5 × 111g/mole

                                                                = 55.5g

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Answer: A

Explanation:

Oxidation is the process through which electrons are gained. This indicates that only organisms on the electron side have the potential to be oxidizing agents. c, d, and e are, by definition, eliminated.

We also know that H+ is in the +1 oxidation state. The same is true for 'H' in H2O... it doesn't change oxidation states

Therefore, the answer must be a) nitrate

Answer:

Option 3

Explanation:

Heat is absorbed, so the reaction is endothermic.

Answer:

I believe it is 68

Explanation:

to convert Celsius to kelvins you must add it to 273.15 for example 29 + 273.15 is 302.15

im so very sorry if im wrong.

The work function is 4.74eV if light frequency [tex]1.40 X 10^{15}[/tex] Hz strike a surface causing photoelectrons to leave with a KE of 1.05 eV.

When light whose frequency is more than the threshold frequency incident on the metal, electrons are emitted. Such electrons are called photoelectrons.

The photoelectric effect is a phenomenon in which a beam of light is projected towards a metal plate and this leads to the ejection of electrons from the metal. The minimum amount of energy required for this ejection of electrons is known as the work function. When the energy of the light beam is less than the work function, then the electrons are not emitted.

The photoelectric effect is represented by the equation:

E = φ + KE  where

E = energy of the incident photons

KE = kinetic energy of photoelectrons

φ = Work function of the metal

This can also be written in terms of frequency as:

h = h₀ +  [tex]\frac{1}{2}[/tex]mv²

h₀= frequency of the incident light beam

m = mass of the electron

v = velocity of the electron

h = Plank's constant 6.623 x 10⁻³⁴Js

Conversion factor: 1eV = 1.602 x 10⁻¹⁹ J

So, 1.05eV = 1.682 10⁻¹⁹ J

Using the formulas,

(6.623 x 10⁻³⁴Js)(1.40x10¹⁵ s⁻¹) = φ + 1.682 x 10⁻¹⁹ J

(9.272 x 10⁻¹⁹) - (1.682 x 10⁻¹⁹) = φ

φ = 7.590 x 10⁻¹⁹ J = 4.74 eV

Hence, the work function is 4.74eV if light frequency 1.40x10^15 Hz strike a surface causing photoelectrons to leave with a KE of 1.05 eV.

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The FORMULA for the limiting reagent is [tex]ZnOH_2[/tex].

4.27 grams of reactant remains after the reaction is complete.

The limiting reagent is the reactant that is completely used up in a reaction and thus determines when the reaction stops.

Given data:

Mass of sulfuric acid = 41.0 grams

Molar mass of sulfuric acid = 98.08 g/mol

Mass of zinc hydroxide = 36.5 grams

Molar mass of zinc hydroxide = 99.424 g/mol

Step 1:moles sulfuric acid = mass sulfuric acid / molar mass sulfuric acid

moles sulfuric acid = 41.0 grams / 98.08 g/mol

moles sulfuric acid = 0.41 moles

Step 2: moles of zinc hydroxide

moles zinc hydroxide = 36.5 grams / 99.424 g/mol

moles zinc hydroxide =0.367 moles

Step 3: Calculate limiting reactant

zinc hydroxide is the limiting reactant. It will completely be consumed.

There will remain 0.41 moles - 0.367 moles = 0.043 moles

This is 0.043 moles x 99.424 g/mol

= 4.27 grams

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Answer:

Explanation:

Mining:

    Mining is when certain substances are removed from the Earth, usually in large quantities. Mining can occur below the surface of the Earth via tunnels and caves. It can also occur at surface level through methods such as strip mining, which removes huge amounts of soil in the process

Rice would not show any negative test with Benedicts solution but will show  blue black color with iodine.

The Benedicts solution is used to test for the presence of reducing sugars in a solution. The brick red color is a positive test for reducing sugars such as glucose.

Owing to the fact that grape does not have starch, it shows a negative test for starch. Rice would not show any negative test with Benedicts solution but will show  blue black color with iodine.

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V=n/M

V=(6.34:125.55 g/mol)/0.72

V=0.07 L = 70 ml

Answer:

Explanation:

To solve problems like this, the very first thing to do is to write out the balanced equation for the process. The reaction is

Zn(s) + HCl(aq) → ZnCl2(aq) + H2(g)

and the balanced equation is

Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2(g)

So, by examining the stoichiometry, you can see that for every mole of Zn, two moles of HCl will be required. In turn, we need to know the number of moles of Zn is represented by 10.4 g. The molecular weight of Zn is 65.38 g/mol so

moles of Zn = 10.4 g/65.38 g/mol = 0.159 moles

and, twice as many moles of HCl is required so

# of moles of HCl required = 2 * 0.159 = 0.318 moles

Question 1

[tex]\text{pH}=-\log(\text{H}^{+})\\\\13=-\log(\text{H}^{+})\\ \\ \text{[H}^{+}]}=1 \times \boxed{10^{-13} \text{ moles per liter}} \\ \\ \text{[H}^{+}] \times \text{[OH}^{-}] =1 \times 10^{-14} \text{ M}\\\\\text{[OH}^{-}]=\boxed{1 \times 10^{-1} \text{ moles per liter}}[/tex]

Question 2

[tex]\text{pH}=-\log(\text{H}^{+})\\\\\text{pH}=-\log(1.0 \times 10^{-4})=\boxed{4}[/tex]

Answer:

OC. Fe³+

Explanation:

Greater reduction potential (bigger positive E value) means that things wants to get electrons. For this, you have to look at the chart that I have attached. Since, Fe3+ has highest E value out of other options, it will likely be reduced.

The species which is most likely to get reduced is Fe³⁺.

Reduction is the process of the addition of electrons and loss of oxygen atoms. It is part of redox reactions.

Redox reactions are the type of reactions in which oxidation and reduction simultaneously take place. Oxidation is the addition of oxygen atoms. Reduction is the removal of oxygen atoms.

Redox reaction can be represented as:

PbO (s) + H₂ (g) → Pb(s) + H₂O (l)

In the above reaction, PbO is getting reduced and H₂ is getting oxidized.

Fe³⁺ is most likely to get reduced because the more positive the value of reduction potential, the more will be its tendency to get reduced.

In the given four species, the value of the reduction potential of Fe³⁺ is the highest.

Values of the reduction potential of four species are:

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Molar concentration of Zn2+ions in a solution is 3.481 mol/lit

The electrode potential value is 59mV

Temperature=298k

What is electrode potential?

equation formed- Zn → Zn2+ + 2e

              from Nernst equation-

E=E cell - 0.059 log [Zn2+]

[zn2+]=3.481 mol/lit

hence, Molar concentration of Zn2+ions in a solution is 3.481 mol/lit

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Answer:

an x-ray a photographic or digital image of the internal composition of something, especially a part of the body, produced by X-rays being passed through it and being absorbed to different degrees by different materials.

examples

Abdominal x-ray.

Barium x-ray.

Bone x-ray.

Chest x-ray.

Dental x-ray.

Extremity x-ray.

Hand x-ray.

Joint x-ray.

Explanation:

its uses

An X-ray is a common imaging test that's been used for decades. It can help your doctor view the inside of your body without having to make an incision. This can help them diagnose, monitor, and treat many medical conditions.

For a system PCl3(g) + Cl2(g) PCl5(g) at equilibrium at 25°C, for which H° = –92.5kJ at 25°C, the ratio of the partial pressure of PCl5 to the partial pressure of PCl3 is will increase

Generally, the equation for chemiecal reaction is mathematically given as

PC3 (g) + C₁₁₂ (g) = PC15 (g) 3

Assuming the addition of some Cl2 gas. The reaction will shift to the right at the invariant volume temperature, maintaining equilibrium. This results in a rise in P9Cl5(g) and a fall in PpCl3(g).

PpCl (g) /PpCl (g) will increase

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The ratio of the partial pressure of PCl₅ to the partial pressure of PCl₃ is will increase for a system PCl₃ (g) + Cl₂ (g) --> PCl₅ (g) at equilibrium at 25°C, for which H° = –92.5kJ at 25°C when some Cl₂ (g) is added at constant volume and temperature.

Generally, the equation for chemical reaction is mathematically given as ;

PCl₃ (g) + Cl₂ (g) --> PCl₅ (g)

Assuming the addition of some Cl₂ gas,

The reaction will shift to the right at the constant volume and temperature, maintaining equilibrium.

This results in a rise in PCl₅ (g) and a fall in PCl₃(g).

Hence, the ratio of the partial pressure of PCl₅ to the partial pressure of PCl₃ is will increases

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