Order the following elements according to the valence numbers from lowest to highest


1. Boron

2. Sodium

3. Chlorine

4. Beryllium

Answer:

Explanation:

As per being a Group 7 element, it would gain one electron, which changes it's charge to 1-. It is therefore negatively charged, having a full outer shell of 8, having its electronic structure to be at 2,8,8.

Answer:

0 K

[tex]{ - \bf{273 \degree C}}[/tex]

298 K

[tex]{ \tt{ = 298 - 273}} \\ = { \bf{25 \degree C }}[/tex]

323 K

[tex]{ \tt{ = 323 - 273}} \\ = { \bf{50 \degree C}}[/tex]

423 K

[tex]{ \tt{ = 423 - 273}} \\ = { \bf{150 \degree C}}[/tex]

1.T=[£+273]

=273

It is because kelvin temperature is absolute zero.

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Answer:

[tex]\boxed {\boxed {\sf A. \ 186.94 \ L}}[/tex]

Explanation:

We are asked to find the original volume of a gas given a change in temperature. Since pressure remains constant, we are only concerned with volume and temperature, so we use Charles's Law. This states the volume of a gas is directly proportional to the temperature. The formula for this law is:

[tex]\frac {V_1}{T_1}= \frac{V_2}{T_2}[/tex]

The gas begins with a temperature of 450 Kelvin, but the volume is unknown.

[tex]\frac {V_1}{450 \ K }= \frac{V_2}{T_2}[/tex]

The gas is cooled to 248.9 Kelvin and the gas occupies a volume of 103.4 liters.

[tex]\frac {V_1}{450 \ K }= \frac{103.4 \ L}{248.9 \ K}[/tex]

Since we are solving for the original volume, we must isolate the variable V₁. It is being divided by 450 Kelvin. The inverse operation of division is multiplication, so we multiply both sides of the equation by 450 K.

[tex]450 \ K \frac {V_1}{450 \ K }= \frac{103.4 \ L}{248.9 \ K}* 450 \ K[/tex]

[tex]V_1= \frac{103.4 \ L}{248.9 \ K}* 450 \ K[/tex]

The units of Kelvin cancel.

[tex]V_1= \frac{103.4 \ L}{248.9 }* 450[/tex]

[tex]V_1= 0.4154278827 \ L *450[/tex]

[tex]V_1= 186.9425472 \ L[/tex]

Round to the nearest hundredth. The 2 in the thousandths place tells us to leave the 4 in the hundredth place.

[tex]V_1 \approx 186.94 \ L[/tex]

The original volume is approximately 186.94 liters and Choice A is correct.

Answer:

Some signs of a chemical change are a change in color and the formation of bubbles. The five conditions of chemical change: color change, formation of a precipitate, formation of a gas, odor change, temperature change.

Answer:

Kinetic energy

Explanation:

Kinetic energy is the energy associated with an object's motion. It is mass and velocity dependent by a directly proportional relationship.

Potential energy is the energy associated with an object's position.

Thermal energy is the energy associated with heat addition or withdrawal.

Kinetic energy is the energy that a body possesses because of its movement, that is, it is the energy that arises when objects are in motion.

Therefore, we can conclude that kinetic energy is the energy produced by its movements that depends on its mass and speed.

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Answer:

depends on the element it's reacting with..

Explanation:

if the another element requires less energy to loose electron then zinc will become negatively charged and hence becomes acidic radical..

normally if it is reacting with element with valency 4 and Atomic number less than it(Ti,Si,C) then it will lose electron and gain positive sign and henve becomes basic radical..

Answer:

A Calorimeter is a device used to measure the amount of heat involved in a chemical or physical process.

Explanation:

Ex- when an exothermic reaction ( accompanied by or requiring absorption of heat)occurs in solution in a calorimeter, the heat produced by the reaction is absorbed by the solution increasing its temperature.

   - When an endothermic reaction (Heat evolving reaction) occurs, the heat required is absorbed from the thermal energy of the solution, decreasing its temperature.

A burning piece of coal which is releasing heat due to its combustion and is transferred to water.

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Answer:

The composition of air can be determined by an experiment which includes passing a known volume of air, measured at a known temperature and pressure, over sufficient amount heated copper granules/powder, and measuring the volume gas remaining after the gas cools down to the temperature at which the first measurement was taken

Oxygen reacts with copper according to the following chemical reaction

2Cu (s) + O₂ (g) → 2CuO (s)

Cupper does not react with the other constituents of air

Whereby the initial volume of air was 100 cm³, we have;

Percentage of oxygen in air = 100 - The final volume reading of the container initially holding the air

When done using am appropriate experimental setup, the percentage of gases remaining equals 79% to 80%, therefore, the percentage composition of oxygen in air is between 20 and 21 percent

Explanation:

Explanation:

because there are 4 Iodines on the left, we'll put. 4 in front of NaI to balance it. This would result in 4 Na on the left, so we'll put a 2 in front of Sodium Sulfate to balance the right side. Now we have 4 Na and I on both side, as well as 2 Sulfate on both sides. Pb is already balanced. The equation is now complete.

Answer:

they are weak forces that attract neutral molecules to one another

Explanation:

particles in liquid or air vibrate and move constantly thus they collide

Answer:

The lighting filters use subtractive properties to bring light of a color to the eye because subtractive color mixing uses white light source with a series of filter to eliminate certain wavelengths of light.

Different colour lights (RBG) uses additive properties to bring light of a certain color to our eyes.

Color synthesis is the art of forming different types of colours from small number of primary colours. The color formed is called a secondary color.

Color synthesis is carried out through the following means:

In additive color synthesis, the three primary colours lights that are combined is Red(R), Blue (B) and Green(G).

The wavelength from the various color light combine to generate white light which is visible to the eye.

Therefore, different colour lights (Red, Blue and Green) uses additive properties to bring light of a certain color(white) to our eyes.

Learn more about color synthesis here:

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Answer:

false tjytyjiy

Explanation:

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The thickness of one button will be 2mm

* N.B: We convert the height of the 12 buttons to same unit (mm)

Then, 2cm = 2 × 10 = 20mm

20mm + 4mm = 24mm

24/12 = 2mm thick

Hence, one button is 2mm thick.

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Answer:

process of depositing a thin layer of any superior metal over an object of a cheaper metal, with the help of electric current

Explanation:

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Answer:

1 . statement is false

2. statement is true

I guess ensuring that you don't suck the insects or specimen collected by ensuring there is a net in the pooter

Answer:

P¹V¹/T¹=P²V²/T² here

P²= 1.25- atm

V²=?

T²=345K

P¹=0.75-atm

V¹=120

T¹=295K

So V²= (0.75 x120/295)x(345/1.25)

Volume of the gas V²= 84.20- ml

Answer:

Solution given:

at first

volume[tex]V_{1}=120.0ml[/tex]

pressure [tex]P_{1}=0.75atm[/tex]

temperature [tex]T_{1}=22+273=295°K[/tex]

after increasing temperature and pressure

volume[tex]V_{2}=xml[/tex]

pressure [tex]P_{2}=1.25atm[/tex]

temperature [tex]T_{2}=70+273=343°K[/tex]

now

[tex]\frac{P_{1}V_{1}}{T_{1}}=\frac{P_{2}V_{2}}{T_{2}}[/tex]

substituting value

[tex]\frac{0.75*120}{295}=\frac{1.25*x}{343}[/tex]

0.305=5x/1372

Doing criss cross multiplication

5x=0.305*1372

x=418.46/5

x=83.69ml

x=84ml

the volume will be 84ml

Answer:

Explanation:

Element -

It is the basic unit of matter, which cannot be broken down into substances by any way but can be combined to form new substances.

It is a pure substance.

It classifies into metals, non-metals, metalloids and noble gases.

Example - Hydrogen, Carbon, Oxygen

Compounds -

It is a combination of two or more elements.

It is a pure substance.

Through chemical reactions, they can be broken down into metals.

Example - Water, Carbon dioxide

Mixtures -

It is a combination of two or more elements or compounds or both.

The substances combined in a mixture are in a particular ratio.

Example - Chalk powder, Washing Soda

Answer:

Zn²⁺ + 2Ag → Zn + 2Ag⁺

Explanation:

According to the reduction potential chart, silver ion (Ag⁺) is a stronger oxidizing agent than zinc (Zn), which is a reducing agent the compared to silver

Therefore, the redox reaction that will occur is that the zinc, Zn, will be oxidized to Zn²⁺ ion, while the silver, Ag²⁺ ion will be reduced to silver deposits Ag, therefore, the zinc will displace the silver in the solution containing silver and zinc ions because zinc is higher than silver in the reactivity series

The reduction potential Zn → Zn²⁺ + 2e⁻ = +0.76

The reduction potential for Ag⁺ + e⁻ → Ag = +0.8

Given that redox reactions are reversible, we get the following likely redux reaction:

Zn(s) + 2Ag⁺(aq) ⇄ 2Ag(s) + Zn²⁺(aq)

Zn²⁺(aq) + 2Ag(s) → Zn(s) + 2Ag⁺(aq) is the reaction most likely to occur.

Explanation:

your answer was correct

Answer:

C. Molecules

Explanation: Water is a compound that conatins molecules hydrogen and oxygen.

Answer: Atoms

Explanation:

Explanation:

A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the electrostatic force of attraction between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bonds.

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Answer:

Check Down

Explanation:

A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the electrostatic force of attraction between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bond.

Answer:

B.electrostatic repulsion by gold nuclei

Explanation:

According to Rutherford's experiment, a thin gold foil was bombarded with alpha particles. Some of the particles passed through the foil undeviated, some were scattered through large angles while some bounced backwards.

It follows that the particles that bounced backwards must have encountered a massive particle of like charge.

The atom is composed of a nucleus which contains positively charged particles. Some of the alpha particles which are positively charged particles bounced back when they encountered the positively charged particles in the nucleus.

Answer: The correct option is B (electrostatic repulsion by gold nuclei).

Explanation:

In the Rutherford's experiment, he used positively charged particles called alpha particles to bombard an atom in order to find out what is inside the atom. Together with two other scientists, Geiger and Marsden, they used a narrow beam of alpha particles emitted from a radioactive source to bombard a thin gold foil. The scattering of the particles from the gold foil was detected by a movable zinc sulphide screen which could be rotated to various positions around the foil.

Each time an alpha particle hit the screen, a visible flash of light or scintillation was produced. This was observed by a microscope attached to the screen. It was then observed that some of the particles followed a straight path through the gold foil while a few where scattered in a backward direction. This was as a result of electrostatic repulsion by gold nuclei which occurs due to the greater part of the mass of the atom was concentrated in a minute nucleus with positive charge.

Answer:

K = [N2] [Cl2]³ / [NCl3]²

Explanation:

The equilibrium expression, K, of a reaction:

aA + bB ⇄ cC + dD

Is defined as the ratio between the multiplication of concentrations of products powered to its reaction coefficient and the multiplication of concentrations of reactants powered to its reaction coefficient as follows:

K = [C]^c[D]^d / [A]^a[B]^b

Now, for the reaciton:

2NCl3 ⇄ N2(g) + 3Cl2(g)

K is:

K = [N2] [Cl2]³ / [NCl3]²

Answer:

[tex]{ \bf{2P _{(s)} + 5Cl _{2(g)} → 2PCl _{5(s)}}}[/tex]

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[tex]\boxed{\pmb{\purple{\sf{2P(s) + 5Cl _{2}(g)\dashrightarrow 2PCl _{5}(s)}}}}[/tex]

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