PLEASE HELP!!!!!
Q1: Give the letter of a substance that is a solid at 20 °C
Q2: Give the letter of a substance that is a liquid at 50 °C

Answer:

ExplaAt high temperatures MgCO3 decomposes to magnesium oxide and carbon dioxide. This process is important in the production of magnesium oxide. This process is called calcining: MgCO3 → MgO + CO2 (ΔH = +118 kJ/mol)

nation:

Answer:

42,07%and 18,90%

Explanation:

Answer:

P2 = 1.94 kPa

Explanation:

Given the following data;

Initial pressure = 2.36 kPa

Initial temperature = 62°C

Standard temperature = 0°C

Conversion:

Kelvin = 273 + C

Kelvin = 273 + 62 = 335 K

Kelvin = 273 + 0 = 273 K

To find the final pressure, we would use Gay Lussac's law;

Gay Lussac states that when the volume of an ideal gas is kept constant, the pressure of the gas is directly proportional to the absolute temperature of the gas.

Mathematically, Gay Lussac's law is given by;

[tex] PT = K[/tex]

[tex] \frac{P1}{T1} = \frac{P2}{T2}[/tex]

Making P2 as the subject formula, we have;

[tex] P_{2}= \frac{P1}{T1} * T_{2}[/tex]

[tex] P_{2}= \frac{2.36}{335} * 273 [/tex]

[tex] P_{2}= 0.0071 * 273 [/tex]

P2 = 1.94 kPa

Answer:

Its electron configuration is: 2 electrons in the K shell (principal quantum number 1), 8 in the L shell (principal quantum number 2), 8 in the M shell (principal quantum number 3), and 2 in the N shell (principal quantum number 4).

Explanation:

Hope this helped!!! xoxo

t!kt0k: preppydreams

(a) distance measured with metre rule or tape rule

    time measured with stopwatch/ stop clock/ timer

    Average speed = total distance / time

(b) (i) decrease in speed

    (ii) Change in speed = a * t

        4.5 m/s

hope this helps......

Answer:

2 L

Explanation:

From the question given above, the following data were obtained:

Molarity of LiF = 2 M

Mole of LiF = 4 moles

Volume =?

Molarity of a solution is simply defined as the mole per unit litre of the solution. Mathematically, it is expressed as:

Molarity = mole / Volume

With the above formula, we can obtain the volume of the solution as shown below:

Molarity of LiF = 2 M

Mole of LiF = 4 moles

Volume =?

Molarity = mole / Volume

2 = 4 / volume

Cross multiply

2 × volume = 4

Divide both side by 2

Volume = 4/2

Volume = 2 L

Therefore, the volume of the solution is 2 L.

a) The genotype is Hh. We simply combine the two given letters together to get this genotype.

b) The phenotype is Widow's peak. The uppercase letter is the dominant allele, while the lowercase is recessive. Any presence of the dominant allele (even a single letter) will mean the dominant phenotype will present itself. We can see that HH leads to Widow's peak phenotype, so that applies to Hh as well. Only when there isn't a dominant allele at all, the genotype hh, is when the recessive phenotype will show up.

Answer:

Lesson Summary. A substance is simply a pure form of matter. In other words, a substance is matter than contains only one type of atom or molecule. Pure substances can be further divided into two sub-categories: elements and compounds.

Explanation:

Radhe Radhe❤

Answer:

true

Explanation:

Answer:

the valency of sodium is one because sodium loses 1 electron to become stable

Answer:

this is the answer

I hope it helps you although

Explanation:

a chemical reaction that absorbs energy is known to be endothermic since heat is being taken in by the reaction. The value of the transition state would be 150 because you have to subtract the product's enthalpy and the reactant's enthalpy to obtain it. A positive value for the transition state also corroborates that the reaction is endothermic.

Answer: Because this does not dissolve in water - it forms a barrier on the surface of the unreacted CaCO3 which prevents any further reaction. A small volume of CO2 is produced , but this stops after a short time . Conclusion: H2SO4 cannot be used with CaCO3 to produce CO2 gas .

Explanation:

Answer:

frick u beotch

Explanation:

SO2+ H2O=H2SO3

H2S+ H2O=H2SO4 +H2

NO2+  H2O= HNO3+NO

Answer:

when d volume of a substance is high, the concentration is gonna b low...

Jus lyk putting much water in just a cube of sugar

Explanation:

So lower volume, higher concentration

What is the formula for potassium sulfate?

[tex]\implies {\blue {\boxed {\boxed {\purple {\sf { K_{2} SO_{4} }}}}}}[/tex]

[tex]\circ \: \: { \underline{ \boxed{ \sf{ \color{green}{Happy\:learning.}}}}}∘[/tex]

Answer:

I HOPE IT'S HELP

Answer: There are many forms of table salt: coarse salt, refined salt, iodized salt. It is a crystalline solid, white to very pale pink or gray in color, obtained from seawater or salt deposits. Salt obtained from seawater has crystals that are smaller or larger than rock salt. In nature, table salt consists mainly of sodium chloride (NaCl), but also a few other minerals (trace minerals). Table salt obtained from rock salt may appear more gray because of traces of trace minerals. Table salt is necessary for the survival of all living organisms, including humans. Table salt is involved in regulating the body's water content (liquid balance).

Answer:

Decomposition Reaction

Answer:

Heat Energy needed (Q) = 68250 J

Energy lost (Q') = 10500 J

Explanation:

Applying,

Q = cm(t₂-t₁)............. Equation 1

Where Q = heat  energy needed, c = specific heat capacity of water, m = mass of water, t₁ = initial temperature, t₂ = final temperature.

From the question,

Given: m = 250 g = 0.25 kg, t₁ = 20.0°C, t₂ = 85.0°C

Constant: c = 4200 J/kg°C

Substitute these values into equation 1

Q = 0.25(4200)(85-20)

Q = 68250 J.

Similarly, heat lost

Q' = cm(t₁-t₂)................. Equation 2

Where Q = heat lost

Given: t₁ = 85°C, t₂ = 75°C

Substitute into equation 2

Q' = 4200(0.25)(85-75)

Q' = 10500 J

Answer: The hydronium [tex](H_{3}O^{+})[/tex] concentration of a solution with a pH of 3.60 is 0.56 M.

Explanation:

pH of a substance is the negative logarithm of concentration of hydrogen ions present in it.

It's formula is; pH = - log [tex][H^{+}][/tex]

When pH of a solution is 3.60 then its hydronium or hydrogen ion concentration is calculated as follows.

[tex]pH = - log [H^{+}]\\3.6 = - log [H^{+}]\\concentration of H^{+} = antilog (-3.6)\\= 0.56[/tex]

Thus, we can conclude that the hydronium [tex](H_{3}O^{+})[/tex] concentration of a solution with a pH of 3.60 is 0.56 M.

Answer:

A helium nucleus

Thre types of radiation

Alpha: Helium nucleus

Beta: Electron

Gamma: Gamma rays

Answer:

The Bohr Model is very limited in terms of size. Poor spectral predictions are obtained when larger atoms are in question. It cannot predict the relative intensities of spectral lines. It does not explain the Zeeman Effect, when the spectral line is split into several components in the presence of a magnetic field.

Explanation:

Answer:

espero que te ayude ........

Answer:

3.85 × 10²³ molecules CO

General Formulas and Concepts:

Atomic Structure

Stoichiometry

Explanation:

Step 1: Define

Identify

[Given] 17.9 g CO

[Solve] molecules CO

Step 2: Identify Conversions

Avogadro's Number

[PT] Molar Mass of C: 12.01 g/mol

[PT] Molar Mass of O: 16.00 g/mol

Molar Mass of CO: 12.01 + 16.00 = 28.01 g/mol

Step 3: Convert

Step 4: Check

Follow sig fig rules and round. We are given 3 sig figs.

3.8484 × 10²³ molecules CO ≈ 3.85 × 10²³ molecules CO

"You have the same number of moles of each." is the true statement.

The mass of Gold and Silver differ, so that first statement can't be true because the quantities are the same. Because a mole measures solely amounts, like a dozen does, you will have the same amount of moles if the quantities are the same.

Answer:

Bases Do not Change the Color of Blue Litmus.

I'd go with Option C.

Sodium Hydroxide.

Answer:

a)22.2°C after adding magnesium

b)17.3°C before adding magnesium

c) 4.9 is change

Answer:

957.7mL

Explanation:

Using the formula below;

CaVa = CbVb

Where;

Ca = concentration of acid (M)

Va = volume of acid (mL)

Cb = concentration of base (M)

Vb = volume of base (mL)

According to the information provided in this question:

Ca = 0.166 M

Cb = 0.013 M

Va = 75mL

Vb = ?

Using CaVa = CbVb

0.166 × 75 = 0.013 × Vb

12.45 = 0.013Vb

Vb =12.45/0.013

Vb = 957.7mL