what is the valency of hydroxide​

Answer:

A- Ca

B- Ca(OH)2

C-CaCO3

D- CaO

Explanation:

Element A is calcium. Calcium reacts with water to form calcium hydroxide (compound B) as follows; Ca(s) + 2H2O(l) ----> Ca(OH)2(s) + H2(g).

When exposed to air, calcium hydroxide (compound B) forms calcium trioxocarbonate IV (CaCO3) which is compound C as follows;

Ca(OH)2(s) + CO2(g) -----> CaCO3(s) + H2O(l)

On heating compound C, the oxide, CaO (D) is formed as follows;

CaCO3(s) ------> CaO(s) + CO2(g)

This oxide reacts with water to yield B again as follows;

CaO(s) + H2O(l) ----> Ca(OH)2(s)

Answer:

it will float if the object is 1g/cm^3(water 's density ) because it is less dense

Answer:

The given hydrocarbon is Butanol

Answer:

+91.7 KJmol-1

Explanation:

Recall that ∆G= -RTlnK

Since ∆G in this case is ∆Grxn and K is the Ksp

Note that the Ksp is the solubility product (as shown by the reaction equation)

∆Grxn is the change in free energy for the reaction, in this case the ionization of the silver iodide into silver and iodide ions.

R= 8.314JK-1 and T =25°C +273 = 298 K (the centigrade temperature must be appropriately converted to its corresponding absolute absolute before proceeding with the calculation)

Hence we can substitute values accordingly;

∆Grxn = -(8.314 × 298 × ln 8.3×10^-17)

∆Grxn = +91.7 KJmol-1

Answer:

Heat energy is the result of the movement of tiny particles called atoms, molecules or ions in solids, liquids and gases. Heat energy can be transferred from one object to another. the transfer or flow from one object to another is called heat.

hopefully this helped :3

Answer:

1) CO₂

2) 0.2551 g

Explanation:

The balanced reactions are:

CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

MgCO₃ + 2HCl → MgCl₂ + H₂O + CO₂

1) The gas produced is CO₂.

2) Calculate mass of CaCO₃:

(0.5236 g) (0.4230) = 0.2215 g CaCO₃

Convert to moles:

(0.2215 g CaCO₃) (1 mol / 100.1 g) = 0.002213 mol CaCO₃

Find moles of CaCO₃:

(0.002213 mol CaCO₃) (1 mol CO₂ / mol CaCO₃) = 0.002213 mol CO₂

Convert to mass:

(0.002213 mol CO₂) (44.01 g / mol) = 0.09738 g CO₂

Calculate mass of MgCO₃:

(0.5236 g) (0.5770) = 0.3021 g MgCO₃

Convert to moles:

(0.3021 g MgCO₃) (1 mol / 84.31 g) = 0.003583 mol MgCO₃

Find moles of MgCO₃:

(0.003583 mol MgCO₃) (1 mol CO₂ / mol MgCO₃) = 0.003583 mol CO₂

Convert to mass:

(0.003583 mol CO₂) (44.01 g / mol) = 0.1577 g CO₂

Total mass of CO₂:

0.09738 g CO₂ + 0.1577 g CO₂ = 0.2551 g CO₂

Answer:

i- In beaker A, sodium chloride will dissolve with water.

  and in beaker B, there will be no reaction.

ii- sodium chloride is soluble in water, while sand is insoluble.

iii- The reaction can be increased by adding more sodium chloride to the beaker.

iv- The sodium chloride will no longer dissolve in the water.

Answer: 12.21

Explanation:

It is well known that the sum of pH + pOH = 14.

To get the pOH of the solution, we subtract 1.79 from 14.

pH + pOH = 14

pOH = 14 - 1.79 = 12.21

pOH = 12.21

The average kinetic energy of colliding particles can be increased by increasing temperature.

B.

Answer:

B

Explanation:

Increasing the Temperature

Answer:

NaHCO₃

Explanation:

Sodium bicarbonate (baking soda) is a chemical compound with the formula NaHCO₃.

Answer:

B. The energy absorbed in the first move is greater than the energy released in the second move.

Explanation:

It takes large amounts of energy for a electron to jump energy levels and the further it moves, the more it takes.

Answer:

B

Explanation:

The energy absorbed in the first move is greater than the energy released in the second move.

Answer: Since oxygen is in group 6 on the periodic table, its valency is  

2 −

and hence so is its oxidation number.

But there are 2 oxygen atoms for each carbon atom so the total negative charge due the oxygen is  

4 −

But since a molecule must have a net charge of zero in the free form, it implies that the oxidation number of the carbon atom must then be  

+ 4

So here we are given that the the velocity of the proton ( V ) is 2.0 × [tex]10^6[/tex] meters / second, with a magnetic field of strength 5.5 × [tex]10^{-3}[/tex]  tesla. If they each form a right angle, they are hence perpendicular to one another, such that ....

F = q( V × B ),

F = q v B( sin ∅ ),

F = q v B( sin( 90 ) )

.... they form the following formula. Let's go through each of the variables in our formula here -

{ F = Magnetic Force ( which has to be calculated ), q = charge of proton (has charge of 1.602 × [tex]10^{19}[/tex] coulombs ), B = magnetic field }

All we have to do now is plug and chug,

F = ( 1.602 × [tex]10^{19}[/tex] )( 2.0 × [tex]10^6[/tex] )( 5.5 × [tex]10^{-3}[/tex] ) = ( About ) 1.8 × [tex]10^{-15}[/tex] Newtons

Answer: hey there, the answer to your question is (E)

Explanation:

Answer:

Its 5

Explanation:

Answer:

Option C. 2000 cm³.

Explanation:

We'll begin by calculating the number of mole in 2 g of Mg. This is illustrated below:

Molar mass of Mg = 24 g/mol

Mass of Mg = 2 g

Mole of Mg =?

Mole = mass /Molar mass

Mole of Mg = 2/24

Mole of Mg = 8.33×10¯² mole.

Next, we shall determine the number of mole of H2 produced from the reaction. This is illustrated below:

Mg(s) + 2H^+ (aq) —› Mg^2+(aq) + H2 (g)

From the balanced equation above,

1 mole of Mg reacted to produce 1 mole of H2.

Therefore, 8.33×10¯² mole of Mg will also produce 8.33×10¯² mole of H2.

Finally, we shall determine the volume of H2 produced. This is illustrated below:

1 mole of H2 occupy 24000 cm³ at room temperature and pressure.

Therefore, 8.33×10¯² mole of H2 will occupy = 8.33×10¯² x 24000 ≈ 2000 cm³ at room temperature and pressure.

Therefore, 2000 cm³ of H2 were obtained from the reaction.

Answer:

B. distance light travels in a year

got it on edge :)

The statement which accurately and best describes a light-year is the total distance which light travels in a complete year

Velocity of light can simply be defined as that fundamental constant that represents the speed of electromagnetic radiation in a vacuum.

The velocity of light = 2.9979 × 10^10cm/s

So therefore, the statement which accurately and best describes a light-year is the distance which light travels in a complete year

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Answer:

Both have densities greater than that of water

Explanation:

The ability of objects to either float or sink in a liquid depends on their relative densities.

If an object is denser than a liquid it will completely sink in it, but if the density of the object is less than that of the liquid, it will sink until the weight of liquid displaced is equal to the weight of the object, then it will finally float in that liquid.

In the case of the stone bead and iron beads dropped into a cup of water, hey both sank to the bottom because they are denser than water.

Answer:

1:put these in sneaker and add water since sulphur is insoluble and the sugar will dissolve and the sand will settle obtain the sulphur

2:filter the mixture of sand and sugar solution to obtain the sand as residue and solution as filtrate

3:using an evaporating dish evaporate sugar solution to saturation not dryness to get crystals.

Answer:

16.83°

Explanation:

The computation of temperature in degrees is shown below:

For this we need to applied the combination of the Clasius Clapyeron equation which is

[tex]ln(\frac{P_2}{P_1}) = \frac{-\Delta Hvap}{R} \times (\frac{1}{T_2}- \frac{1}{T_1})[/tex]

Where

P_2 and P_1 represents the pressure of vapor at point 1 and 2

dH = Here we use J/mol

R = 8.314 J/mol K

T1 and T2 represent the temperature of Saturation temperature for point 1 and 2

Now

we have to change the negative signs

i.e

[tex]ln(\frac{P_2}{P_1}) = \frac{\Delta Hvap}{R} \times (\frac{1}{T_1}- \frac{1}{T_2})[/tex]

As we know that

dHvap for water = 40.67 kJ/mol

T1 = 373 K,

T2 = x

P1 = 14.7 psi;

P2 = 11.2 + 14.7 = 25.9 psi

Now put the values to the above formula

So,

[tex]ln (\frac{25.9}{14.7}) = \frac{40670}{8.314} \times (\frac{1}{373}- \frac{1}{T_2})\\\\T_2 = - (ln (\frac{25.9}{14.7})\times \frac{8.314}{40670} - \frac{1}{373})^{-1}[/tex]

After solving this

T_2 = 389.836K

T_2 = 389.836 - 273

T_2 = 116.836 °C

Therefore by 16.83°,  it becomes higher

The Option C is correct precipitation is concentrated in the season

Hope it help

Answer:

C) precipitation is concentrated in one season

Explanation:

edge 2020

Answer:

A is true NaCl

B is false K2Br

C is true

D false its only 0.03 percent

E is true

Answer:

Tectonic Plates

Explanation:

Answer:

Tectonic plates

Explanation:

Answer:

Channel rays or anode rays are a historical name for positive ion beams, due to their first embodiment. They were indeed observed experimentally for the first time by a German physicist, Eugen Goldstein, in 1886.

Explanation:

Answer:

Mg  

Explanation:

The standard reduction potentials are

                                              E°/V

Au³⁺(aq ) + 3e⁻  ⟶  Au(s);     1.42

Hg²⁺(aq)  + 2e⁻  ⟶  Hg(l);     0.85

Ag⁺(aq)    +   e⁻  ⟶  Ag(s);    0.80

Cu²⁺(aq)   + 2e⁻ ⟶  Cu(s);   0.34

Mg2+(aq) + 2e- ⟶  Mg(s);   -2.38

The more negative the standard reduction potential, the stronger the metal is as a reducing agent.

Mg is the only metal with a standard reduction potential lower than that of Cu, so

Only Mg will react spontaneously with Cu²⁺.

Answer:

B. Mg

Explanation:

Answer:

11 Protons

Explanation:

Na-23 shows the mass of the element as 23. Therefore subtract 12 neutrons from the mass to get # of protons which is = to atomic #.

The atomic number of 23-Na is 11. It can be calculated from the number of protons present in the nucleus of an atom.

The atomic number is a fundamental property of an element and represents the number of protons found in the nucleus of an atom. It uniquely identifies each element on the periodic table. In a neutral atom, the atomic number also indicates the number of electrons present in the atom, as the number of protons and electrons in an atom are equal.

For example, hydrogen has an atomic number of 1, indicating that it has one proton in its nucleus. Oxygen has an atomic number of 8, indicating that it has eight protons in its nucleus.

The atomic number determines the element's position in the periodic table and provides important information about its properties and behavior.

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The number of protons and neutrons together makes the total atomic mass of the element. The atom of chromium has 28 neutrons. Thus, option b is correct.

An atomic mass is the property of an element that defines the number of protons and neutrons of the atom placed in a periodic table. The atomic mass is represented at the lower half of the atomic symbol.

The atomic mass is the sum of the neutrons and the protons that are held together in the nucleus of the atom as a concentrated mass. The atomic number is given as,

Atomic number = number of protons + number of neutrons

Given,

The atomic mass of chromium = 52

Number of protons = 24

Substituting values above:

52 = 24 + number of neutrons

number of neutrons = 52-24

= 28

Therefore, the number of neutrons of a chromium atom is 28.

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Answer: option b, 28

Answer:

22

Explanation:

22

Answer:

12

Explanation:

To get to this answer you have to look at the number first. So the given number is 12.47 and you need 2 sig figs.

To help you understand this more start off by underlining the first 2 numbers because 2 sig figs are needed.  12.47

Now you want to look at the number after the underlined (I bolded that number). 12.47

If the number is above 5 then you would round the previous number up by one but in this case it is 4 so you do not increase the number. Hence, you getting 12 as your final answer.

Hope this helped! Let me know if you have any questions.

Answer:

A composite material is a material made from two or more constituent materials with significantly different physical or chemical properties that, when combined, produce a material with characteristics different from the individual components.

Explanation:

you're welcome

Answer:

The vinegar is not enough to neutralize the pool.

Explanation:

The [OH⁻] in the pool is 1.0x10⁻¹mol / L. To know how many moles of OH⁻ are in the solution, you must calculate volume of the pool thus:

V(pool) = πr²h

Where r, radius is d/2 = 12m/2 = 6m  and h is deep of the pool = 10m

V(pool) = π(6m)²*10

V(pool) = 1131m³

As 1m³ = 1000L:

1131m³  × (1000L / 1m³) = 1131000L in the pool.

And moles of OH⁻ are:

1.0x10⁻¹mol / L ₓ 1131000L = 131100 moles of OH⁻ are in the pool

The neutralization of OH⁻ with H⁺ is:

OH⁻ + H⁺ → H₂O

That means to neutralize the pool you must add 131100 moles of H⁺.

The H⁺ concentration in a vinegar pH = 2 is:

pH = -log [H⁺]

2 = -log [H⁺]

1x10⁻²M = [H⁺]

4L are just 4x10⁻² moles of [H⁺]. As you need 131100 moles of H⁺: