According to astronomers , the age of the universe is estimated to be

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Answer 1

Answer:

The age of the universe is approximately 13.8 billion years old. The universe is constantly expanding. A universe with a low density of matter is older than a matter – dmominated one. To determine the density and composition of the universe, scientists rely on missions such as NASA’s Wilkinson Microwave Anisotropy Probe spacecraft. They measure the thermal radiation left from Big Bang.

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What is observed when an iron bar is dipped into a solution of silver nitrate

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Answer:

I think it will start to have a greenish color and get lighter

Explanation:

Is rubber band stretching physical or chemical

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Answer:

$\boxed {\boxed {\sf Physical \ change}}$

Explanation:

A chemical change, as the name suggests, must result from a change in the chemical makeup and new substances are produced. A very common example is metal rusting.

A physical change can be observed without a change in chemical composition. No new substances are produces. Ripping paper and an ice cube melting are physical changes.

A rubber band stretching is a physical change. No new substances are made and the chemical makeup remains the same.

Answer:

physical

Explanation:

this is a physical action to create a change. does not involve chemicals or elements

One mole of ice at 0°C is added to two moles of water at 50°C under a constant external pressure of 1 atm. This process is carried out in a thermally insulated vessel, such that no heat can escape the vessel. When equilibrium is reached, all of the ice has melted. Given: Δ H f u s i o n ∘ ( H 2 O a t 0 ∘ C ) = 6.01 k J m o l C p ( H 2 O , l i q u i d ) = 75 J m o l K a) (7 Points) Calculate the final temperature of the mixture (in °C). Show all work to support your answer.

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Answer:

T2 = 29.79°C

Explanation:

Equliibrium signifies that heat loss = heat gained

Heat gained by Ice;

H = ML

Mass, M = Number of moles * Molar mass = 1 * 18 = 18g

l = 6.01 k J m o l = 334 J/g

C = 4.186 J/g

H = 18(334)

H = 6012

Heat lost by water

H = MCΔT

H = 18 * 4.186 * (50 - T2)

H = 3767.4 - 75.348T2

Since H = H, we have;

6012 = 3767.4 - 75.348T2

- 75.348T2 = 3767 - 6012

T2 = 2245 / 75.348

T2 = 29.79°C

Identify each of the following as either a physical change or a chemical change. Explain your answers.A. a piece of wood is sawed in half.
B. milk turns sour.
C. melted butter solidifies in the refrigerator.

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A. physical
B. Chemical
C.Physical

Answer:

A would be Physical

B would be Chemical

and C would be Physical

Explanation:

A would be physical because the wood is physically changing

B would be chemical because it's still milk but it now had clumps called curds and a very sour taste

C would be physical because the melted butter is physically changing from melted butter to solid butter.

Hope this helps.

The compound HCI is an example of a (n)

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The compound HCl is an example of a strong acid. It fully dissociates into its respective ions H+ and Cl-.

HCI is an example of hydrochloric acid.

PLEASE HELP CHEM BABES I HAVE BEEN CRYING FOR A WHILE NOW 1. Calculate the mass of nitrogen dioxide (NO2) present in a 0.831 L container if the pressure is 100 kPa at a temperature of 27 oC. R = 8.31 kPa x L / mol x K. (K = oC + 273).

2. A 33.2 L tank contains 280 g of compressed helium. If the pressure inside the tank is 700.0 kPa, what is the temperature of the compressed gas? You must convert the mass of helium into moles using the molar mass of He. The conversion factor will be 1 mol / molar mass of helium. R = 8.31 kPa x L / mol x K

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Answer: See below

Explanation:

1. To calculate the mass, you know you can convert by using molar mass. Since mass is in grams, we can use molar mass to convert moles to grams. This calls for the Ideal Gas Law.

Ideal Gas Law: PV=nRT

We manipulate the equation so that we are solving for moles, then convert moles to grams.

n=PV/RT

P= 100 kPa

V= 0.831 L

R= 8.31 kPa*L/mol*K

T= 27°C+273= 300 K

Now that we have our values listed, we can plug in to find moles.

$n=((100kPa)(0.831L))/((8.31kPa*l/molK)(300K))$