why are the metals like gold and silver prefferred for making jwellery?

Answer

Climate, because this describes what the weather is like over a long period of time.

Answer:

23 protons, 23 electrons, 33 neutrons

Explanation:

I don't know why my answer got deleted but no worries, I can answer again. The number of protons and electrons is equal to the atomic number which is 23 and the number of neutrons is 56 - 23 = 33 because atomic mass denotes the number of protons and neutrons.

Answer: Hg +2

Explanation:

Hg+2 is formed when mercury loses two electrons.

Hg  ------>  Hg +2  +  2 e-

Answer:

Hg+2 (D) is the correct answer

Explanation:

the person above me is correct, hope this helps, have a good one

Answer:

C: The surroundings heat up and the system decreases in volume.

D: The surroundings heat up and the system does not change volume.

B: The surroundings heat up and the system expands in volume.

A: The surroundings get cold and the system decreases in volume.

Explanation:

The most exothermic reactions are those that release heat, that is to say, they give up the heat as it cools and the surroundings heat up.

As for endothermics, that is, those that absorb or capture the heat of the medium, they are variables that cool the environment that surrounds them and increase their internal temperature

Answer:

% purity of limestone = 96.53%

Explanation:

Question (4).

Weight of impure CaCO₃ = 25.9 g

Molecular weight of CaCO₃ = 40 + 12 + 3(16)

                                              = 100 g per mole

We know at S.T.P. number of moles of CO₂ = 1 and volume = 22.4 liters

From the given reaction, 1 mole of CaCO₃ reacts with 1 mole or 22.4 liters of

CO₂.

∵ 22.4 liters of CO₂ was produced from CaCO3 = 100 g

∴ 1 liter of CO₂ will be produced by CaCO₃ = [tex]\frac{100}{22.4}[/tex]

∴ 5.6 liters of CO₂ will be produced by CaCO₃ = [tex]\frac{100\times 5.6}{22.4}[/tex]

                                                                              = 25 g

Therefore, % purity of CaCO₃ = [tex]\frac{\text{Weight calculated}}{{\text{Weight given}}}\times 100[/tex]

                                                 = [tex]\frac{25}{25.9}\times 100[/tex]

                                                 = 96.53 %

Answer:

The answer is Aluminum

Hope this helps you

Answer:

idk but i tryed

Explanation:

The simplest way to use the periodic table to identify an element is by looking for the element’s name or elemental symbol. The periodic table can be used to identify an element by looking for the element’s atomic number. The atomic number of an element is the number of protons found within the atoms of that element.

Answer:

When dividing the measurements 400 g/32.2 cm³, the answer has  3

significant figures.

Explanation:

400 g/32.2 cm³ = 12.422 g/cm³.

Our answer cannot have more significant figures than the number with the least significant figures. Since both the numerator and denominator have 3 significant figures, our answer will also have 3 significant figures.

So  400 g/32.2 cm³ = 12.4 g/cm³ to 3 significant figures

So, when dividing the measurements 400 g/32.2 cm³, the answer has  3

significant figures.

Answer:

CH3CH3, 1,3- dichloro-2,2- dibromo, 2-butyne, cyclopentane, 2,3- dimethylbut-2-ene, 2,2,4,4- tetramethlpenta-3-one.

Explanation:

This problem or question has to do with spectroscopy. Spectroscopy is one of the Important aspect of physical Chemistry. It is important because it helps in the identification of chemical samples or compounds. The Nuclear Magnetic field work generally on the principle of absorption of energy.

The following compounds as given in the question above shows singlet in the 1H NMR spectrum.

(1). CH3CH3: shows singlet in the 1H NMR spectrum at 0.86 ppm.

(2). 1,3- dichloro-2,2- dibromo; shows singlet.

(3). 2- butyne shows singlet

(4). Cyclopentane shows singlet.

(5). 2,3 - dimethylbut-2-ene shows singlet.

(6). 2,2,4,4- tetramethlpenta-3-one shows singlet.

Kindly note that I have used the IUPAC naming system to name the Compounds in the question above.

Answer:

3.01

[tex] \times [/tex]

10-22

moles=mass/RMM

moles=140/28

=5moles

1mole=6.02*10-23

5moles=?

=3.01*10-22

hope this is helpful

Answer:

The correct option is -286 kJ

Explanation:

The given parameters are

C(s) + O₂(g) → CO₂(g)   ΔHf = -394 kJ

H₂(g) + 12O₂(g)→H₂O ΔHf = -242 kJ

2C(s) + 3H₂(g)→C₂H₆(g)  ΔH = -84 kJ

Te given equation is C₂H₆(g) + 7/2O₂(g) →2CO₂(g) + 3H₂O(l)

The heat of formation or enthalpy of combustion = Heat of formation of the products - Heat of formation of the reactants

The enthalpy of combustion of the reaction = 2*(-394) + 3*(-242)- ((-84)+7/2*0)) = -1,430 kJ

Given that the reaction consists of one mole of C₂H₆(g), we have;

The enthalpy of combustion of one mole of C₂H₆(g) = -1,430 kJ

Therefore, the enthalpy of combustion of 0.2 mole of C₂H₆(g) = -1,430 kJ × 0.2 = -286 kJ

The correct option = -286 kJ.

Answer:

Positive 1,430

Explanation:

Answer:

Cellular respiration:

[tex]C_6H_{12}O_6+6O_2\rightarrow 6CO_2+6H_2O[/tex]

Explanation:

Hello,

In this case, the law of conservation of mass states that matter cannot be created nor destroyed but modified, therefore, typical examples are the raft chemical reactions in nature or carried out in a laboratory. Thus, a typical one that could be daily found is in the cellular respiration wherein glucose and oxygen are converted into carbon dioxide, water and energy for us to use it in our daily activities. It is chemically represented by:

[tex]C_6H_{12}O_6+6O_2\rightarrow 6CO_2+6H_2O[/tex]

Law of conservation of mass is verified as six carbon atoms are before and after the chemical reaction, twelve hydrogen atoms are before and after it and eighteen oxygen atoms as well.

Best regards.

Answer:

Air-drying clothes conserves more water than using an electric clothes dryer.

Answer: The added pressure could cause pilots to become disorinated

Explanation:

Answer:

When sound molecules stack up in front of high-speed flights, loud noises are produced that can damage the ears.

Answer:

because it showed how the electron could orbit the nucleus without falling into it.

Answer:

Explanation:

A

Answer:

Subatomic particles are the proton (1 amu), neutron (1 amu), and electron (0 amu)

Explanation:

Atomic mass unit (amu; dalton): A unit of mass equal to exactly 1/12 the mass of one 12C atom, or 1.660538921 x 10−27 kg. This is the approximate mass of one proton or one neutron. It is the basis of atomic weights.

Answer:

[tex]\boxed{\mathrm{see \: below}}[/tex]

Explanation:

Protons have a mass of 1 amu (atomic mass unit).

Electrons have a mass of [tex]\frac{1}{1840}[/tex] amu (atomic mass unit).

Neutrons have a mass of 1 amu (atomic mass unit).

Answer:

Sublimation

Explanation:

Sublimation refers to the process by which the change of matter takes place directly from solid to liquid state. The matter from the solid-state directly changes into the gaseous state without changing into the liquid state. More energy is required in this process. This is an endothermic reaction. Dry ice is the solid carbon dioxide sublimes in the air.

Explanation:

1 mol of Ba(OH)2 = 2 moles of HCl

Answer:

131.26 g

Explanation:

From the balanced equation,

2 moles of N₂H₄reacts with 1 mole of N₂O₄ to give 3 moles of N₂

Now number of moles of N₂H₄ present in 100 g N₂H₄ is n = 100 g/molar mass N₂H₄.

Molar mass N₂H₄ = 2 × 14.01 g/mol + 1 × 4 g/mol = 28.02 g/mol + 4 g/mol = 32.02 g/mol

n₁ = 100/32.02 = 3.123 mol

Also

Now number of moles of N₂O₄ present in 200 g N₂O₄ is n = 200 g/molar mass N₂O₄.

Molar mass N₂O₄ = 2 × 14.01 g/mol + 16 × 4 g/mol = 28.02 g/mol + 64 g/mol = 92.02 g/mol

n₂ = 200/92.02 = 2.173 mol

Since the mole ratio of N₂H₄  to N₂O₄ is 2 : 1, We require 2 × 2.173 mol N₂H₄  to react with 2.173 mole N₂O₄  

Number of moles of N₂H₄ required is 4.346. But the number of moles of N₂H₄  present is 3.123 so N₂H₄  is the limiting reagent.

So, from the equation, 2 moles of N₂H₄ produces 3 moles of N₂

Therefore number of mole N₂ = 3/2 moles of N₂H₄ = 3/2 × 3.123 mol = 4.6845 mol

From n = m/M where n = number of moles of nitrogen gas = 4.6845 mol and M = molar mass of nitrogen gas = 28.02 g/mol and m = mass of nitogen gas.

m = nM = 4.6845 mol × 28.02 g/mol = 131.26 g

So the mas of nitrogen gas produced is 131.26 g

Answer : The initial concentration of HI and concentration of HI at equilibrium is, 0.27 M and 0.386 M  respectively.

Solution :  Given,

Initial concentration of H_2 and I_2 = 0.11 M

Concentration of H_2 and I_2 at equilibrium = 0.052 M

Let the initial concentration of HI be, C

The given equilibrium reaction is,

    H_2(g)+I_2(g)\rightleftharpoons 2HI(g)

Initially               0.11   0.11            C

At equilibrium  (0.11-x) (0.11-x)   (C+2x)

As we are given that:

Concentration of H_2 and I_2 at equilibrium = 0.052 M  = (0.11-x)

The expression of K_c will be,

K_c=\frac{[HI]^2}{[H_2][I_2]}

54.3=\frac{(C+2(0.058))^2}{(0.052)\times (0.052)}

By solving the terms, we get:

C = 0.27 M

Thus, initial concentration of HI = C = 0.27 M

Thus, the concentration of HI at equilibrium = (C+2x) = 0.27 + 2(0.058) = 0.386 M

Answer:

X is sodium hydroxide (caustic soda, NaOH)

y is sodium (Na)

Explanation:

The process of industrial electrolysis of sodium chloride solution by which chlorine and sodium hydroxide (caustic soda) can be produced is known as the chlor-alkali process as follows;

2NaCl + 2H₂O → Cl₂ + H₂ + 2NaOH

Given that the compound X is formed from a element y which is in the form of a pellet, we have;

The element in the above reaction that can exist as pellet is the silver white metallic sodium pellet

Therefore, the compound X is NaOH and the element y is sodium, Na.

Answer:

as mass and the square of speed is directly proportional to the the kinetic enegry so, more there will be mass and speed there will be more kinetic enegry.

Answer:

The boiling point of the substances

Explanation:

Because Boiling point is an intensive property.

Answer:

H % = 11.11%

O % = 88.89%

Explanation:

atomic weight of H = 1

atomic weight of O = 16

each molecule of water contains 2 atoms of H and one atom of O

hence molecular weight of water = 18

H % = 2 x 100/18 = 11.11%

O % = 16 x 100/18 = 88.89%

Answer:

-H= 11.19%

-O= 88.81%

Explanation: the answer above mine is incorrect!,  i just did it and i got it right, the answer is h= 11.19% and O= 88.81% hope it helps!

Answer: Wheat flour, edible oil, egg white, lettuce preservative, meat or poultry marinade, vegetable antibacterial wash.

Explanation:

hydrogen peroxide is used as a bleaching agent in some food

I hope this helped

Your answer is A. What is the composition of air?

The question that can be answered by science is What is the composition of air? The correct option is A.

Science is a subject that deals with the components of the earth. It has a wide variety of components of earth. Like planets and meteorites. Plants, animals, and other creatures. Nature, trees, and other abiotic factors.

Science gives answers to the secrets of the earth, and they unravel the mysteries of nature and the earth. They solve the mysteries of air, water, and other natural processes.

So the composition of air can be told by science. The air is made up of a mixture of gases. Air is present in the atmosphere. It is needed for breathing, and it is an important component of life because it provides oxygen to the body.

The correct option is A. What is the composition of air?

To learn more about science, refer to the below link:

https://brainly.com/question/12842883

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