Which of the following is a halogen?
O A. Neon (Ne)
B. Iodine (1)
O C. Oxygen (0)
O D. Potassium (K)

Answer:

Concept of chemi-fluorescence

Explanation:

A glow stick usually consists of two chemicals in a larger plastic tube: , a base catalyst (mostly sodium salicylate), and a suitable dye (sensitizer, or fluorophor). This creates an exergonic reaction when mixed together.

When a glow stick is bent, the flurophor which is a chemical that easily re-emits light upon excitation in smaller capsules is released into the other substance, there by causing it to emit radiation/light in the uv-visible region. The brightness and longevity of the glow stick is determined by varying the concentration of these chemicals.

I hope this explanation clarifies things.

Answer:

HeyA ❤

Let us consider the mass of oxygen as 1 g.

Mass of lead obtained from yellow oxide = 3.45 g – 0.24 g = 3.21 g

Mass of oxygen = 0.24 g

The mass of lead that combines with 0.24 g of oxygen = 3.21 g

Therefore, mass of lead that combines with 1 g of oxygen = 3.21/ 0.24 = 13.4 g

Mass of lead obtained from brown oxide = 1.227 g – 0.16 g = 1.067

Mass of oxygen = 0.16g

The mass of lead that combines with 0.16 g of oxygen = 1.067 g

Therefore, mass of lead that combines with 1 g of oxygen = 1.067/ 0.16 = 6.66 g

Now, ratio of masses of lead which combines with a fixed mass of oxygen = 13.4 : 6.66

= 2 :1

Thus, masses of lead which combine with the fixed mass of oxygen are in the ratio of (2:1) i.e. small whole numbers.

Hence, the law of multiple proportions is illustrated.

Follow meehhhh Piper ❤

Answer:

D. 48 N down

Explanation:

Given that:

Mass of climber = 85 kg, Tension on rope = 785 N, acceleration due to gravity = 9.8 m/s²

To calculate the net force on the climber, we need to first calculate the weight of the climber. Since the climber is affected by the earth gravity, the weight of the climber is the product of his mass and the acceleration due to gravity, therefore:

Weight = mass × acceleration due to gravity = 85 kg × 9.8 m/s² = 833 N

The weight of the climber is acting downwards while tension on the rope is acting upwards, therefore:

Net force on the climber = 785 N - 833 N = - 48 N

This means that the net force on the climber is 48 N downwards

Answer:

48 N down

Explanation:

Ayepecks

Answer:

Recycling and reuse of materials

Explanation:

One of the greatest problems facing the human population is the problem of solid waste disposal. The menace of solid waste disposal has led to the idea of landfills. Land fills are depressions on the earth surface prepared for the purpose of solid waste disposal.

The most important approach towards solid waste disposal is the idea of recycling of materials. A material can be collected after use and processed into the same material or serve as a precursor in another manufacturing process. This means that no waste is generated as the materials which are supposed to be disposed of as solid waste are processed into other useful materials. This will reduce the volume of solid wastes generated that may need to be disposed in a landfill.

Answer:

There are many ways to reduce the amount of trash sent to landfills: Recycle as much as possible. Limit disposable products, and use reusable ones whenever possible. Reuse, sell, or pass along old items instead of throwing them away.

Explanation: PLATO

Explanation:

What are the two oxidation states of sulphur in sodium thiosulphate ? In thiosulphate, two sulphurs have oxidation state of -2 and +6. (as per suggestions). Sulphur bonded to three oxygen is considered to have +6 (Sulphur A) and other sulphur has -2 (Sulphur B).

Answer:

oppositely charged ions in a chemical compound

Explanation:

Answer:

Between ions

Explanation:

Answer:

Liner shape

Explanation:

Because BeCl2 has 2 bond pair and no lone pair it means it will have liner shape and 180 degree angle.

Answer:

liner compound

Explanation:

Answer:

E. None of the above

Explanation:

Answer:

32. Opcion E

Explanation:

ZO₂ podemos entenderlo como dióxido de Z

1 mol de ZO₂ contiene 1 mol de Z y 2 moles de O₂ por lo que si la masa molar es de 64 g/mol, podemos plantear lo siguiente

Masa de Z + 2 masa de O = 64 g/mol

Sabemos que la masa del oxígeno es 16 g/mol

x + 2. 16 g/mol = 64 g/mol

x = 64 - 32 →  32 g/mol

La masa atómica coincide con la masa molar, por lo tanto la masa atomica de Z es 32.

Considerando la definición de masa molar, la respuesta correcta es la opción E: La masa atómica de Z debe ser 32.

La masa molar es la masa de un mol de una sustancia, la cual puede ser un elemento o un compuesto, esto es, es la relación entre la cantidad de sustancia y su masa.

En otras palabras, la masa molar es la cantidad de masa que una sustancia contiene en un mol.

En la tabla periódica, se puede encontrar la masa molar de los elementos, también llamada masa atómica o peso atómico.  

Para calcular la masa molar de un compuesto, también llamado masa o peso molecular, se debe sumar la masa molar de los elementos del compuesto multiplicado por su cantidad en el compuesto.

Entonces, en este caso, siendo la masa molar del oxígeno (O) 16, y la masa molar del compuesto ZO₂ 64, y denominando x a la masa molar de Z, entonces la masa molar del compuesto puede expresarse como:

x + 2×16= 64

Resolviendo:

x + 32= 64

x=64 -32

x=32

Finalmente, la respuesta correcta es la opción E: La masa atómica de Z debe ser 32.

Aprenda más:

Answer:

2835 J

Explanation:

Take the specific heat capacity of water as 4.2 J/ g°C.

Energy (heat) = mass x specific heat capacity x change in temperature

(E= mcΔT)

E = 27 x 4.2 x (45-20)

E = 2835 J

Explanation:

It is given that,

Initial orbit of electrons, [tex]n_i=4[/tex]

Final orbit of electrons, [tex]n_f=2[/tex]

We need to find energy, wavelength and frequency of the wave.

When atom make transition from one orbit to another, the energy of wave is given by :

[tex]E=-13.6(\dfrac{1}{n_f^2}-\dfrac{1}{n_i^2})[/tex]

Putting all the values we get :

[tex]E=-13.6(\dfrac{1}{(4)^2}-\dfrac{1}{(2)^2})\\\\E=2.55\ eV[/tex]

We know that : [tex]1\ eV=1.6\times 10^{-19}\ J[/tex]

So,

[tex]E=2.55\times 1.6\times 10^{-19}\\\\E=4.08\times 10^{-19}\ J[/tex]

Energy of wave in terms of frequency is given by :

[tex]E=hf[/tex]

[tex]f=\dfrac{E}{h}\\\\f=\dfrac{4.08\times 10^{-19}}{6.63\times 10^{-34}}\\\\f=6.14\times 10^{14}\ Hz[/tex]

Also, [tex]c=f\lambda[/tex]

[tex]\lambda[/tex] is wavelength

So,

[tex]\lambda=\dfrac{c}{f}\\\\\lambda=\dfrac{3\times 10^8}{6.14\times 10^{14}}\\\\\lambda=4.88\times 10^{-7}\ m\\\\\lambda=488\ nm[/tex]

Hence, this is the required solution.

f(Hz) = 6.17 × 10¹⁴

E(J) = 4.09 × 10⁻¹⁹

E(ev) = 2.56

Answer:

1. A compound is a group of elements that cannot be separated by physical methods.

NaCl is a compound becuse it cannot be separated by physical methods.

It consists of postive and negative ions.

It can be separated only by chemical reactions.

2. (a) A is a mixture of iron and sulphur and it is in liq form.

(b) Gas B is hydrogen gas and it has sharp pungent irritating smell.

(c) It is a physical change.

Explanation:

Answer:

[tex]\boxed{\mathrm{view \: explanation}}[/tex]

Explanation:

This is an irreversible reaction, we cannot derive any [tex]\mathrm{K_c}[/tex] expression for it. The [tex]\mathrm{K_c}[/tex] expression can only be derived for reversible reactions and not irreversible reactions. We cannot derive the [tex]\mathrm{K_c}[/tex] expression for this reaction.

Answer: Double displacement reaction

Explanation:

Double displacement reaction is defined as the reaction where exchange of ions takes place.

The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.

The chemical reaction between aqueous magnesium sulfate and aqueous sodium carbonate is represented as:

[tex]MgSO_4(aq)+Na_2CO_3(aq)\rightarrow Na_2SO_4(aq)+MgCO_3(s)[/tex]

Answer: 0.52849 j /g °C

Explanation:

Given the following :

Mass of metal = 36g

Δ Temperature of metal = (28.4 - 99)°C = - 70.6°C

Mass of water = 70g

Δ in temperature of water = (28.4 - 24.0) = 4.4°C

Heat lost by metal = (heat gained by water + heat gained by calorimeter)

Quantity of heat(q) = mcΔT

Where; m = mass of object ; c = specific heat capacity of object

Heat lost by metal:

- (36 × c × - 70.6) = 2541.6c - - - - (1)

Heta gained by water and calorimeter :

(70 × 4.184 × 4.4) + (12.4 × 4.4) = 1288.672 + 54.56 = 1343.232 - - - - (2)

Equating (1) and (2)

2541.6c = 1343.232

c = 1343.232 / 2541.6

c = 0.52849 j /g °C

Answer:

See the answer below

Explanation:

In chemistry, indicators are substances that are capable of changing colors with respect to the pH. Each indicator has its characteristic color in acidic pH and another characteristic color in alkaline pH.

Methyl orange indicator appears red in acidic solution and yellow in basic solutions. Phenolphthalein is usually colorless in acidic solutions and appears pink in basic solutions. A red litmus paper will turn blue in alkaline solutions while a blue litmus paper will turn red in acidic solutions.

Answer:

727.7 torr

Explanation:

Since the gas was collected over water, it is likely to be saturated with water vapour and the total pressure is given as;

Ptotal = Pgas + Pwater

From the question;

Ptotal = 751 torr

Pgas = ?

Pwater = 23.8 torr

Making Pgas subject of equation, we have;

Pgas = Ptotal - Pwater

Pgas = 751 torr - 23.8 torr

Pgas = 727.7 torr

Answer:

A

Explanation:

the increase in the temperature let's the particles to collide more so it increases the rate of reaction.

Answer:

I think the answer is option A.

Explanation:

Because when the temperature increases, the kinetic enegry increases which creates the effective collisions which lets the chemical to react.

Hope it helps..

Answer:

Neutral substance is a substance that show no acid or base properties.

Explanation:

Neutral substance is a substances that show no acid or base properties, has an equal number of hydrogen and hydroxyl ions and does not change the color of litmus paper.

Answer:

They release no substance

Explanation:

Since the substance is neutral, nothing will be released from it.

Answer:

C

Explanation:

because valence electrons are located at the last energy level

Element Grouping Quick Check:

1. Which element has two valence electrons?

D. calcium

2.Based on its position in the periodic table, which element would have seven valence electrons?

A. Chlorine

3. Which phrase describes a valence electron?

C. An electron in the outer energy level of an atom

4. Which phrase best describes a period on the periodic table?

A. A row of elements

5. Which two elements have the same number of energy levels with electrons in them?

A. Boron and Oxygen

Hope this helps!

Answer:

the answer for the question is 40 mL

Answer:

Scientific Classification. Classification, or taxonomy, is a system of categorizing living things. There are seven divisions in the system: (1) Kingdom; (2) Phylum or Division; (3) Class; (4) Order; (5) Family; (6) Genus; (7) Species. ... Species are identified by two names (binomial nomenclature)

Explanation:

Answer:

1) 0.1077 moles

2) 137043.2 moles

3) 180.186 grams

4) 6.53×10²² molecules or formula units

5) 1.505×10²³ ions

6) 90.626 grams

7) 0.555 moles

Explanation:

1) The number of moles, n = Mass of the substance/(Molar mass of the substance)

The molar weight of PO₄⁻³ is 94.971 g/mol

The number of moles in 10.23 g of PO₄⁻³ is n =10.23/94.971 = 0.1077 moles

The number of moles in 10.23 g of PO₄⁻³ = 0.1077 moles

2) The number of molecules of Na₂CO₃ in one mole of Na₂CO₃ is given by the Avogadro's number, [tex]N_A[/tex] = 6.02 × 10²³ molecules

Therefore, the number of moles in 8.25 × 10²⁸ molecules of Na₂CO₃ is found by determining how many Avogadro's number of molecules are in 8.25 × 10²⁸ molecules of Na₂CO₃ as follows;

The number of moles in 8.25 × 10²⁸ molecules of Na₂CO₃ = (8.25 × 10²⁸)/(6.02 × 10²³) = 137043.2 moles

The number of moles in 8.25 × 10²⁸ molecules of Na₂CO₃ = 137043.2 moles

3) The molar mass of CH₂O = 30.031 g/mol

Therefore, the mass of 6 of CH₂O = 6 moles × 30.031 g/mol = 180.186 grams

The mass of 6 of CH₂O = 180.186 grams

4) The molar mass of NaCl = 58.44 g/mol

The number of moles of NaCl in 6.34 g of NaCl 6.34/58.44 = 0.1085 moles

1 formula unit of NaCl = 1 molecule of NaCl

The number of molecules in one mole of  a substance =  [tex]N_A[/tex] = 6.02 × 10²³

Therefore, the number of molecules in  0.1085 moles of NaCl = 6.02 × 10^(23) × 0.1085 = 6.53×10²² molecules or formula units

5) The number of ions per mole of any substance is give by Avogadro's number, [tex]N_A[/tex] = 6.02 × 10²³ ions,

The number of ions in 0.25 moles of Cu⁺² = 0.25×6.02 × 10²³ ions = 1.505×10²³ ions

The number of ions in 0.25 moles of Cu⁺² =  1.505×10²³ ions

6) The molar mass of CH₄ = 16.04 g/mol

The number of moles, n, in 3.4×10²⁴ = 3.4×10^(24)/(6.02×10^(23)) = 5.65 moles 5.65*16.04

The mass of 5.65 moles of CH₄ = 5.65 moles × 16.04 g/mol = 90.626 grams

The mass of 3.4×10²⁴ molecules of CH₄ = 90.626 grams

7) The density of water = 1 g/mL

The volume of the water 10 mL

The mass of the water = Volume × Density = 10 mL × 1 g/mL= 10 grams

The molar mass of water = 18.015 g/mol

The number of moles of water in 10 g  of water = mass/(Molar mass) = 10/18.015 = 0.555 moles.

Answer:

The answer is option A.

longer than visible light

Hope this helps you

Answer:

electromagnatic waves

Explanation:

Answer:

B. Because ionic compounds do not exist in discrete molecules -- they exist in crystal lattices.

Explanation:

A property of ionic compounds is that they form crystal lattice structures. Ionic compounds are crystals of many cations and anions bonded together. There is no molecule of ionic compounds because there is no single unit of the compound.

Hope this helps.

Answer:

a chemical change

Explanation:

a physical change is mostly identified even without indicators i.e candle wax about forming a new acid or base I guess we have to include a ph scale to ascertain since the salt can be acidic but not necessarily an acid

Answer: The answer is A, a chemical change has occurred

Explanation:

I’m just a jenious

Answer:

Elements with unpaired valence electrons in the outer orbital are paramagnetic. Elements that are predicted to exhibit paramagnetic behavior may exhibit ferromagnetic behavior. Elements that contain only paired valence electrons are diamagnetic.

Answer:

Hydrogen gas (H₂) + Oxygen gas (O₂) → Water (H₂O)

Explanation:

Hydrogen reacts with oxygen to form water. The reactants are hydrogen and oxygen and the product is water.

Answer:

Word Equation:

Hydrogen + Oxygen = Water

Hydrogen gas reacts with Oxygen gas to give Water.

The chemical Reaction is as follows:

    [tex]2H_{2} + O_{2}[/tex]   =>    [tex]2H_{2}O[/tex]

Answer:

Difference in temperature.

Explanation:

Conduction is the movement of heat energy through a substance or from one substance to another by direct contact of atoms and molecules. Heat moves directly from one molecule to another. The heat energy speeds up the movement of the atoms and they collide with other molecules setting them into faster motion.

Answer:

Explanation:ifk