please help me this is due soon i really need help :'c
************24 POINTS!*********

Answer:

i think c

Explanation:

:D

Answer:

because cycle is a prosess that goes through multiple stages

Explanation:

.

Results are neither precised nor accurate.

In the Given Actual density of silver  =10.5 g / cm^3

Measured values of silver  density = 14.2 g/cm^3

14.0g/cm^3

7.25g/cm^3

We have to  find whether the measurements given are accurate or precise.

so , Density can be defined as the ratio of mass to volume. The formula for calculation of density is shown below :

Density = Mass / Volume

The units of density is generally g / ml.

The results are said to be accurate if our measured value exactly matches with our true value.

In case of precision ,all the measured values should be near to each other or should differ only by 0.1 or 0.2.

So in this case the measured values are not precised nor accurate because it does not matches with true value also.

Hence , the results are neither precised nor accurate.

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Answer:

Ultraviolet

Explanation:

It doesn't use much energy and so it creates ultraviolet light.

Explanation:

Typically, only one element is present, so all atomic radii are the same. -Metallic bonding is not directional. -Nearest neighbor distances tend to be small in order to lower bond energy.

Answer:

A chemical change has occurred

Explanation:

Given reaction expression:

      CaCO₃ →  CaO  +  CO₂

The reaction is a decomposition reaction in which a compound is dissociated into simple products.

The reason why the products have different properties than the reactants is because a chemical change has occurred.

The products of the decomposition of calcium carbonate have different properties because a chemical change has occured in the reaction to form new substances.

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b is your best bet hope this helps

Answer:

True

True

Temperature

Explanation:

Answer:

Osmosis is a process which occurs when there is a difference in solute concentration between two solutions separated by a semipermeable membrane. A semipermeable membrane allows passage of water but not of solutes. The passage of water occurs because of a pressure difference of water between the two solutions

Answer:

The correct answer is HOF gas.

Explanation:

Based on the given information, the helium atoms effuses three times faster in comparison to the gas X.

The rate of effusion is determined by,

r is inversely proportional to 1/√M, here M is the molecular mass of the gas.

and r is inversely proportional to 1/t, here t is the time taken for effusion.

Thus, t is directly proportional to √M

The molecular mass of He is 4.

tHe = tX/3 (Here tx is the time taken for gas X)

The molecular mass of X is not known.

tX/tHe =√Mx/MHe

3 = √Mx/4

By squaring both the sides we get,

9 = Mx/4

Mx = 36

36 is the molecular mass of gas HOF, that is, (1+16+19 = 36). Hence, the gas X is 36.

Explanation:

Cellulose fibers, structural proteins, and other polysaccharides help to maintain the shape and form of the cell. Additional functions of the cell wall include: Support: The cell wall provides mechanical strength and support. It also controls the direction of cell growth.

Answer:

temperature

amount

Explanation:

Under the postulate of Boyle's law, both temperature and amount(number of moles) are kept constant.

  According to Boyle's law "the volume of a fixed mass of gas varies inversely as the pressure changes if the temperature is constant"

 Based on the premise of this law, both temperature and amount of substance is kept constant.

Answer:

234.213

Explanation:

Moles of Nickel x 58.70 = Grams

3.99 x 58.70 = 234.213

When 25.0g of Zn reacts, mols of HCl are consumed 0.7648 moles HCl

Write down the balanced chemical equation for this one replacement reaction first.

Zn(s)+2HCl(aq)→ZnCl2(aq)+H2(g)↑⏐

Now take note of the 2:1 mole ratio of reaction between the two reactants. This demonstrates that the reaction will always use up two times as much hydrochloric acid as zinc metal.

As you are aware, a solution's molarity indicates the number of moles of solute—in your case, hydrochloric acid, HCl—that are present in one liter of the solution.

The molarity of the hydrochloric acid solution is reported to be

3.05 mol L−1. This indicates that for every 1 L of solution, 3.05 moles of hydrochloric acid are produced. Remember this for later. You are aware that the reaction needs 25.0 g of zinc.

By using the molar mass of zinc, you can convert this mass to moles.

25 g per mole Zn

65.38g = 3.824 moles of zinc

n order for this many moles of zinc to react, you'd need

0.3824moles Zn⋅2amoles

HCl 1 mole Zn=0.7648 moles HCl

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Answer:

c

Explanation:

use %composition given to calculate emperical 4mular

The empirical formula of the compound having 57.5% Na, 40.0% O, and 2.5% H is NaOH (Option C)

Divide by their molar mass

Na = 57.5 / 23 = 2.5

O = 40 / 16 = 2.5

H = 2.5 / 1 = 2.6

Divide by the smallest

Na = 2.5 / 2.5 = 1

O = 2.5 / 2.5 = 1

H = 2.5 / 2.5 = 1

Thus, the empirical formula of the compound is NaOH

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Answer:

opp

Explanation:

Answer:

0.954

Explanation:

1000 grams is 1 kg

954 grams is 954/1000 kg or 0.954

Answer:

Proton

Explanation:

The kinetic energy of 429 kJ and the specific heat of the substance is 9059 g kJ °C

The kinetic energy is given as ,

K.E = 1/2 m[tex]v^{2}[/tex]

Where m = mass = 1599 kg

v = velocity  = 83.4 km/h = 23 m/s

Putting the value mass and velocity in equation ( i ) we get ,

K.E = 1/2 × 1599 kg × 23 m/s × 23 m/s = 429074.86 J = 429 kJ

Specific heat is calculated as ,

Q = mcΔT

mass of the substance ( m ) = 56.87 g

c = 1475 J

ΔT = 138.4 °C - 30.0 °C = 108 °C.

Putting the value of mass , change in temperature and heat absorbed in equation ( ii ) we get ,

Q = 56.87 g × 1475 J × 108 °C = 9059391 gJ°C = 9059 g kJ °C

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The acceleration of the cylinder in m/s2 is 0.973 meters per seconds squared.

Acceleration is the change of velocity with time. The unit is usually meters per seconds squared.

mass = 4.3 kg

radius = 0.4m

angle of inclination, ∅ = 0.15 radians

acceleration of the cylinder in m/s^2

= ( g + sin ∅ ) / 1 + 0.5

= ( 9.81 + sin 0.15 ) / 1.5

take note angle is in radians not degrees

= 1.46 / 1.5

= 0.973 meters per seconds squared

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Answer:

Thermal energy (also called heat energy) is produced when a rise in temperature causes atoms and molecules to move faster and collide with each other. The energy that comes from the temperature of the heated substance is called thermal energy.

Explanation:

will this help you

Answer:

the answer is your a awesome person

The concentration of OH⁻ ions will become 10 times the initial concentration.

A more useful approach to express the concentration of hydrogen ions is on the pH scale, which is the logarithm of the reciprocal of the hydrogen ion concentration in gram moles per liter. The concentrations of the hydrogen ion (H+) and the hydroxyl ion (OH) are both equal to 10⁻⁷ in a neutral solution. The pH of seven is neutral.

Solution pH 1 equals 8.

Solution's pH is 2 = 9.

pOH₁ = 14 - 8 = 6

pOH₂ = 14 - 9 = 5

OH₁⁻ = 10⁻⁶

OH₂⁻ = 10⁻⁵

Ratio = 10⁻⁵ / 10⁻⁶ = 10

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Answer:

C)a mass number of 38

Explanation:

yes

Answer:

It's because the NaCl and MgCl2 is shorter and easier to remember

Answer:

1.67 moles

Explanation:

From the balanced equation of reaction:

                     [tex]SO_2 + 2H_2S -> 3S + 2H_2O[/tex]

1 mole of sulfur dioxide, SO2, is required to produce 3 moles of sulfur, S.

If 1 mole SO2 = 3 moles S, then, how many moles of SO2 would be required for 5 moles S?

     Moles of SO2 needed = 5 x 1/3

                   = 5/3 or 1.67 moles

Hence, 1.67 moles of SO2 would be required to produce 5.0 moles of S.

Answer: 1.7

Explanation:

The percent mass of lead in tetraethyl lead is 64.1%.

The percent by mass of an element in a compound is determined by taking the ratio of the atomic mass of the element and the molar mass of the compound and then multiply by 100%

atomic mass of Pb = 207

atomic mass of C = 12

atomic mass of H = 1

Molar mass of  tetraethyl lead: 207 + 12 * 2 * 4  + 1 * 5 * 4

Molar mass of  tetraethyl lead = 323 g/mol

Percent mass of Pb = 207/323 × 100%

Percent mass of Pb = 0.6408 × 100%

Percent mass of Pb = 64.1%

In conclusion, the percent mass of lead in tetraethyl lead is 64.1%.

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