pls help need it now as I don't know the answer

Answer:

4.26m

Explanation:

Molality , m, is an unit of concentration in chemistry defined as the ratio between moles of solute (In this case, NaCl) and kg of solvent (In this case, water).

To solve the question we need to find the moles of NaCl and the mass of water in kg:

Moles NaCl -Molar mass: 58.44g/mol-:

11.7g * (1mol / 58.44g) = 0.200 moles

Mass of Water in kg:

47g * (1kg / 1000g) = 0.047kg

Molality is:

0.200 moles / 0.047kg =

4.26m

Answer:

B. 1:2

Explanation:

Molar ratio depicts the relationship between the number of moles of two substances. The chemical equation in this question is as follows:

2H2 + O2 → 2H2O

This question is asking to identify the molar ratio of O2 to H2O in the equation. Since 1 mole of oxygen gas (O2) produces 2 moles of water (H2O). Hence, the O2 to H2O molar ratio is 1:2.

Answer:

57 mL

Explanation:

To make things clear, when 769 mL of ethanol were mixed with 507 mL of water, the resulting volume was not (769+507) 1276 mL, but a lower value. This is because of the interactions between liquid molecules.

First we calculate how many grams of ethanol are there in 769 mL, using the given density:

Then we convert 606.97 g of ethanol into moles, using its molar mass:

Now we calculate the actual volume of the solution, using the definition of molarity:

Finally we convert 1.219 L to mL, and calculate the difference in volume:

Answer: 300 g

Explanation: I guessed and got it right

420 liter of volume is occupied by 300 grams of methane gas at standard temperature and pressure (STP).

Ideal gas equation of methane gas at STP (standard temperature pressure) can be written as:

PV = nRT, where

P = pressure = 1 atm

V = volume = 420 L (given)

R = universal gas constant = 0.082 L.atm / k.mole

T = absolute temperature = 273 K

n = no. of moles to find?

Putting all these values in the above equation and calculated for the n:

n = (1 × 420) / (0.082 × 273) = 18.76 moles

Now we calculate mass of methane by the definition of moles as:

n = W/M, where

M = molar mass of methane = 16 g/mole

W = to find?

W = 18.76 × 16 = 300.2 grams or 300grams.

Hence, option (c) is correct i.e. 300 grams of methane occupy 420 L volume.

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conduction is the characteristic of sound makes it possible for bats to fly in the dark without hitting any objects

one of the property of sound is pitch which  is an important property where the perception of frequency of sound take place by human ear within the range of human hearing, higher is the frequency of the sound the higher will be its pitch and a lower frequency means a lower pitch.

The loudness of sound is another property  can be determined by amplitude which  is a measure of the magnitude of the maximum disturbance of sound.

The speed of the sound is  the sound waves travel through the medium is called the speed of sound and it is different for different mediums, travels fastest in solids.

When sound waves hit the  solid  it reflects back to the same medium as it follows laws of reflection.

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Answer:

The mass of water produced is 4.29 g.

Explanation:

Given;

reacting mass of ethane, C₂H₆ = 2.5 g

reacting mass of oxygen, O₂ = 5.0 g

The balanced combustion reaction is given as follows;

2C₂H₆   +   7O₂ ---------------->  4CO₂    +   6H₂O

Based on the balanced equation above;

                                     requires

7.0 moles of oxygen ----------------------->   2.0 moles of ethane

                                   requires

5.0 g of oxygen      -------------------------->  x gram of ethane

x = (2 x 5) / 7

x = 1.43 g

Ethane is in excess of 1.07g (2.5 g - 1.43g)

Now, determine the mass of water produced by 1.43 g of ethane;

                                   requires

2.0 moles of ethane ----------------------->   6.0 moles of water

                                   requires

1.43 g of ethane      -------------------------->  y  gram of water

y = (6 x 1.43) / 2

y = 4.29 g

Therefore, the mass of water produced is 4.29 g.

D is the answer -3                            m              

Answer:

Acceleration = 3 meter per second square

Explanation:

Acceleration (A) = rate of change in velocity

so,

=》A =

[tex] \frac{18 - 9}{3} [/tex]

Where time = 3 seconds

=》

[tex] \frac{9}{3} [/tex]

=》

[tex]3[/tex]

so, acceleration =

[tex]3m {s}^{ - 2} [/tex]

Answer:

I will draw how the city looks like

Answer:

Sulfur tetra fluoride

Explanation:

Answer and Explanation:

El bicarbonato de sodio (o carbonato ácico de sodio, NaHCO₃) es utilizado como antiácido debido a que neutraliza al ácido clorhídrico (HCl) en el estómago. Al ser disuelto en agua, el NaHCO₃ se disocia en iones como sigue:

NaHCO₃ → Na⁺ + HCO₃⁻

El anión bicarbonato (HCO₃₋) sufre hidrólisis, aceptando H⁺ del agua y  liberando iones hidroxilo (OH⁻):

HCO₃⁻ + H₂O → H₂CO₃ + OH⁻

Por lo tanto, la solución de NaHCO₃ es básica y sus aniones OH⁻ pueden neutralizar los H⁺ del HCl en el estómago, reduciendo la acidez.

AnswerB:

Explanation:

Heat can travel from one place to another in different ways. The different methods of heat transfer are conduction, convection and radiation. Here heat transfers from the glass to the ice through conduction.

The process of transmission of energy from one particle of the medium to another with the particles being in direct contact with each other is defined as the conduction. It is also known as the thermal conduction or heat conduction.

In conduction an area of higher kinetic energy transfers thermal energy towards the lower kinetic energy area. Here a transfer of heat energy occurs from tea molecules to the ice cube. Due to the transfer of heat melting of ice occurs.

As the ice melts, the tea starts cooling while heating the ice cube. So the ice cools down the tea. The tea will be melted by the ice here.

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Answer: Sodium chloride is an ionic solid, and when it dissolves in water, its individual sodium and chloride ions are dissociated from one another. Sugar molecules, on the other hand, maintain the bonds between their constituent atoms when dissolved, and thus remain as whole molecules in the solution.

Explanation: Here's why: Salt is about 25% more dense than sugar. Therefore a teaspoon of salt weighs more than a teaspoon of sugar by almost 25%. Your dissolving test would not be accurate because you would be starting out with a larger mass of salt than sugar.

Answer:

first answer

Explanation:

Answer:

2 hard working men fix water spout for the community

Answer: The pressure of nitrogen will be 2.0 atm

Explanation:

According to ideal gas equation:

[tex]PV=nRT[/tex]

P = pressure of gas = 1.0 atm

V = Volume of gas = 10.0 L

n = number of moles = ?

R = gas constant =[tex]0.0821Latm/Kmol[/tex]

T =temperature =[tex]297K[/tex]

[tex]n=\frac{PV}{RT}[/tex]

[tex]n=\frac{1.0atm\times 10.0L}{0.0820 L atm/K mol\times 297K}=0.41moles[/tex]

Now again using ideal gas equation :

[tex]P=\frac{nRT}{V}=\frac{0.41mol\times 0.0821Latm/Kmol\times 297K}{5.0L}=2.0atm[/tex]

Thus pressure of nitrogen will be 2.0 atm

Answer:

14

Explanation:

Mass number is just the value of the protons and neutrons added, in this case its 14

Answer:

220g

Explanation:

Please mark as brainliest

Answer:

temperate

Explanation:

Answer:

A. 0.48mol O2

Explanation:

The balanced equation is given as follows:

2CH3OH + 3O2 → 2CO2 + 4H2O

This shows that 2moles of CH3OH is required to react with 3 moles of O2

If 0.32 moles of CH3OH are reacted, then;

0.32 × 3/2 moles of O2 is required

= 0.96/2

= 0.48mol of O2

QUESTION :

ANSWER :

Answer:

Magnesium Chloride

Explanation:

The formula of a compound is written based on the valency of each bonded atoms. The formulas  Mg₂(SO₄)₃, Rb₃As are incorrect. Such compounds does not exist.

The formula of a chemical compound is written based on the number of atoms participated in bonding.   Magnesium is second group element having two valence electrons.

Magnesium thus donates its two electrons into the bonding atom or group. The sulphate group SO₄ have a valency of 2 it gains two electrons from Mg when bonded.

Thus the formula of magnesium sulphate being MgSO₄ and not Mg₂(SO₄)₃. Similarly Rb is a second group metal having two valence electrons. Its valency being two. As is a halogen with valency one. Thus they cannot form a compound like Rb₃As.

Hence, option a and b are incorrect formulas.

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Answer:

algee

Explanation:

Answer:

2 electron shells

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Answer: 3

Explanation: 5 times a number would be 5x, then increase that by 4 is 5x+4.  The problem then says 5x + 4 ≥ 19.  If we solve for x then we get x ≥ 3 so x has to be greater than or equal to 3, so the smallest number it could be is 3.  You can even try any number smaller than 3 and see it doesn't work.  even something like 2.9